U.S. SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                   FORM U-9C-3




                     QUARTERLY REPORT PURSUANT TO RULE 58 OF
                 THE PUBLIC UTILITY HOLDING COMPANY ACT OF 1935

                For the quarterly period ended September 30, 2003
                                               ------------------




                      FirstEnergy Corp. (File No. 70-09501)
--------------------------------------------------------------------------------
                      (Name of Registered Holding Company)

                     76 South Main Street, Akron, Ohio 443
--------------------------------------------------------------------------------
                    (Address of Principal Executive Offices)





                                FirstEnergy Corp.


                     Quarterly Report Pursuant to Rule 58 of
                 the Public Utility Holding Company Act of 1935

                For the quarterly period ended September 30, 2003
                                               -------------------



                                Table of Contents
                                -----------------

  Item
   No.                                 Title                              Page
  -----          -------------------------------------------------        ----
     1           Organization Chart                                        1-4

     2           Issuances and Renewals of Securities and
                 Capital Contributions                                       5

     3           Associate Transactions                                    6-7

     4           Summary of Aggregate Investment                             8

     5           Other Investments                                           9

     6           Financial Statements and Exhibits:

                     A - Financial Statements                            10-11

                     B - Exhibits                                           12

                     C - Certificate of FirstEnergy Corp.                   12

                 Signature                                                  13




  Note:      All dollar amounts shown in this Form U-9C-3 are expressed in
  ----       thousands unless otherwise noted.





                                                    ITEM 1 - ORGANIZATION CHART


                                                           Energy (ERC)
                                                           or Gas (GRC)      Date of      State of   Percentage of Voting  Nature of
            Name of Reporting Company                    Related Company  Organization  Organization   Securities Held     Business
---------------------------------------------------      ---------------  ------------  ------------ --------------------  ---------
FirstEnergy Corp. (a)

                                                                                                              
    FirstEnergy Ventures Corp. (b)
       Bay Shore Power Company (d)                             ERC         01/26/1998      Ohio             100.0            (h)
       Centerior Energy Services, Inc. (d)                     ERC         06/01/1994      Ohio             100.0            (i)
       Eastroc Technologies, LLC (c)                           ERC         04/30/1996      Delaware          50.0 **         (j)
       Engineered Processes, Ltd. (c)                          ERC         12/30/1996      Ohio              50.0 **         (j)
       Warrenton River Terminal, Ltd. (d)                      ERC         09/03/1996      Ohio             100.0            (k)

    FirstEnergy Facilities Services Group, LLC (b)
       Ancoma, Inc. (e)                                        ERC         04/20/1953      New York         100.0            (g)
       Dunbar Mechanical, Inc. (e)                             ERC         07/16/1956      Ohio             100.0            (g)
       Edwards Electrical & Mechanical, Inc. (e)               ERC         02/28/1968      Indiana          100.0            (g)
       Elliot-Lewis Corporation (e)                            ERC         04/01/1948      Pennsylvania     100.0            (g)
        A.A. Duckett, Inc.                                     ERC         03/01/1973      Delaware         100.0            (g)
        Sautter Crane Rental, Inc.                             ERC         12/10/1991      Pennsylvania     100.0            (l)
        E-L Enterprises, Inc.
          Modern Air Conditioning, Inc.                        ERC         04/27/1965      Florida          100.0            (g)
            Airdex Air Conditioning Corporation                ERC         01/18/1995      Florida          100.0            (g)
          R.L. Anderson, Inc.                                  ERC         08/28/1961      Florida          100.0            (g)
       L.H. Cranston and Sons, Inc. (e)                        ERC         01/02/1951      Maryland         100.0            (g)
       Roth Bros., Inc. (e)                                    ERC         09/06/1947      Ohio             100.0            (g)
       The Hattenbach Company (e)                              ERC         03/21/1969      Ohio             100.0            (m)
       R.P.C. Mechanical, Inc. (e)                             ERC         04/21/1959      Ohio             100.0            (g)
       Spectrum Controls Systems, Inc. (e)                     ERC         04/18/1988      Ohio             100.0            (g)

    FirstEnergy Solutions Corp. (b)                            ERC         08/08/1997      Ohio             100.0            (n)
       FirstEnergy Engineering, Inc. (f)                       ERC         08/09/1996      Ohio             100.0            (v)

    GPU Diversified Holdings, LLC (b)                                      08/03/2000      Delaware         100.0            (t)
       GPU Solar, Inc.                                         ERC         11/07/1997      New Jersey        50.0 **         (u)
       GPU Distributed Power, Inc. *                           ERC         02/29/2000      Delaware         100.0
       EnviroTech Investment Fund I, LP                        ERC                                            9.9 **         (w)
       EnerTech Capital Partners II, LP                        ERC                                           1.82 **          (w)


*    Inactive
**   Set forth the percentage of interest held directly or indirectly by FirstEnergy Corp.

                                                                 1





                                                                 ITEM 1 - ORGANIZATION CHART (Continued)


                                                           Energy (ERC)
                                                           or Gas (GRC)      Date of      State of   Percentage of Voting  Nature of
            Name of Reporting Company                    Related Company  Organization  Organization   Securities Held     Business
---------------------------------------------------      ---------------  ------------  ------------ --------------------  ---------

FirstEnergy Corp. (a) (Continued)

                                                                                                              
    The Alliance Participants Administrative and
       Startup Activities Company, LLC (c)                     ERC         12/22/2000      Delaware         10.0% **         (o)

    PowerSpan Corp. (c)                                        ERC         05/01/1997      Delaware         18.63 **         (p)

    Kinetic Ventures I, LLC (c)                                ERC         04/15/1997      Delaware         11.11 **         (q)

    Kinetic Ventures II, LLC (c)                               ERC         12/07/1999      Delaware         14.28 **         (q)

    Nth Power Technologies II, LLC (c)                         ERC                                            8.2 **         (r)

    Active Power, Inc. (c)                                     ERC                                          0.006 **         (s)

    Utility.com, Inc. (c) *                                    ERC                                            5.0 **         (n)

    Automated Power Exchange, Inc. (c)                         ERC                                           1.16 **         (n)


*    Inactive
**   Set forth the percentage of interest held directly or indirectly by FirstEnergy Corp.


                                                                 2





                     ITEM 1 - ORGANIZATION CHART (Continued)

(a)     FirstEnergy  Corp.,  a  registered  holding  company,  holds  securities
        directly or  indirectly  in the  energy-related  companies set below its
        name.
(b)     These  companies are direct  wholly owned  subsidiaries  of  FirstEnergy
        Corp.
(c)     FirstEnergy  Corp.  owns an  interest  directly or  indirectly  in these
        energy-related companies or venture capital funds set below its name.
(d)     These  companies are direct  wholly owned  subsidiaries  of  FirstEnergy
        Ventures Corp.
(e)     These  companies are direct  wholly owned  subsidiaries  of  FirstEnergy
        Facilities Services Group, LLC.
(f)     This company is direct wholly owned subsidiary of FirstEnergy  Solutions
        Corp.
(g)     This  subsidiary  provides  HVAC  equipment  installation  and services,
        facilities management, and energy management.
(h)     This  subsidiary  owns and operates a petroleum  coke disposal  facility
        that will  supply  steam for the Bay Shore  Power  Plant and to BP Amoco
        Corporation.
(i)     This subsidiary  provides various consulting  services related to energy
        management and procurement.
(j)     This subsidiary holds the patent on plaster, which is manufactured using
        the by-Products of coal-fired generation facilities.
(k)     This subsidiary  owns facilities for the  transloading of bulk materials
        (primarily  coal) on the  Ohio  River.  The coal is in part  used by the
        FirstEnergy Operating Companies at various generation facilities.
(l)     This subsidiary provides crane rental services.
(m)     This subsidiary provides  refrigeration sales and services to commercial
        entities.
(n)     This  subsidiary  engages  in the  brokering  and  marketing  of  energy
        commodities.
(o)     This entity was created to manage the financial and other affairs of the
        ten members of the Alliance Regional Transmission Organization.
(p)     This  company  was  formed to  utilized  advanced  technology  to reduce
        emissions of NOx,  SO2 and  particulate  matter from utility  generation
        facilities.
(q)     This venture capital fund is focus on early stage companies  involved in
        energy-related fields and technology.
(r)     This  venture  capital  fund is focus on  emerging  technologies  in the
        global energy industry.
(s)     This company is a developer of flywheel energy storage system for use in
        uninterruptible power supply and other power quality applications.
(t)     This   energy-related   company   holds   securities   directly  in  the
        energy-related company set below its name.
(u)     This subsidiary is involved in the development and  commercialization of
        photovoltaics.
(v)     This subsidiary provides engineering services.
(w)     An investment fund which invests in energy-related technology.

                                        3




                     ITEM 1 - ORGANIZATION CHART (Continued)


            Narrative Description of Activities for Reporting Period
            --------------------------------------------------------

            None.


                                        4




                              ITEM 2 - ISSUANCES AND RENEWALS OF SECURITIES AND CAPITAL CONTRIBUTIONS



                                 Type of       Principal                             Company to      Collateral     Consideration
                                 Security      Amount of     Issue or    Cost of    whom Security    Given with        Received
Company Issuing Security         Issued        Security      Renewal     Capital     was Issued       Security    for Each Security
---------------------------      --------      ---------     --------    -------    -------------    ----------   -----------------
                                                                                   
          None.



                                    Company Contributing              Company Receiving           Amount of Capital
                                          Capital                          Capital                  Contribution
                                    --------------------        ----------------------------      -----------------

                                                                                                
                                    FirstEnergy Corp.           GPU Diversified Holdings LLC          $  400

                                    FirstEnergy Corp.           PowerSpan Corp.                       $2,740



Note:     The information provided in Item 2 presents the activities of the reporting period only.
----


                                                                 5





                                                  ITEM 3 - ASSOCIATE TRANSACTIONS


Part I - Transactions Performed by Reporting Companies on Behalf of Associate Companies


                                                                                                                            Total
                                                                                                                            Amount
Reporting Company Rendering Services        Associate Company Receiving Services         Types of Services Rendered         Billed
------------------------------------        ------------------------------------         --------------------------         ------

                                                                                   
Warrenton River Terminal, Ltd.              FirstEnergy Generation Corp.                 Loading, unloading and storage
                                                                                         of coal and petcoke

Centerior Energy Services, Inc.             FirstEnergy Solutions Corp.                  Energy consulting services

Dunbar Mechanical, Inc.                     FirstEnergy Generation Corp.                 HVAC equipment installation

Roth Bros., Inc.                            Ohio Edison Company                          HVAC services

Roth Bros., Inc.                            FirstEnergy Generation Corp.                 HVAC services

Elliot-Lewis Corporation                    Jersey Central Power & Light Company         HVAC services

Elliot-Lewis Corporation                    Metropolitan Edison Company                  HVAC services

Sautter Crane Rental, Inc.                  Jersey Central Power & Light Company         Crane rental

Sautter Crane Rental, Inc.                  Metropolitan Edison Company                  Crane rental

Bay Shore Power Company                     FirstEnergy Generation Corp.                 Sale of steam

FirstEnergy Solutions Corp.                 FirstEnergy Generation Corp.                 Natural gas procurement &
                                                                                         scheduling services


Note:   The information  provided in Item 3 presents the activities of the reporting  period only. The amounts  required under the
----    caption "Total Amount Billed" are being filed pursuant to request for confidential treatment.


                                                         6






                                            ITEM 3 - ASSOCIATE TRANSACTIONS (Continued)


Part II - Transactions Performed by Associate Companies on Behalf of Reporting Companies



                                                                                                                           Total
                                                                                                                           Amount
Associate Company Rendering Services    Reporting Company Receiving Services     Types of Services Rendered                Billed
------------------------------------    ------------------------------------     --------------------------                ------

                                                                           
FirstEnergy Service Company             GPU Diversified Holdings LLC             Legal and certain general and
                                                                                 administrative services

FirstEnergy Generation Corp.            Bay Shore Power Company                  Sale of fuel oil

FirstEnergy Generation Corp.            Bay Shore Power Company                  Sale of emission allowances

FirstEnergy Generation Corp.            Bay Shore Power Company                  Plant operation & maintenance services

FirstEnergy Service Company             FirstEnergy Solutions Corp.              General and administrative services


Note:   The information  provided in Item 3 presents the activities of the reporting  period only. The amounts  required under the
        caption "Total Amount Billed" are being filed pursuant to request for confidential treatment.


                                                                 7







                                             ITEM 4 - SUMMARY OF AGGREGATE INVESTMENT


Investments in energy-related companies:

                                                                                                              
   Total average consolidated capitalization as of  September 30, 2003*         $21,521,805                            Line 1
       Total capitalization multiplied by 15% (line 1 multiplied by 0.15)         3,228,271                            Line 2
       Greater of $50 million or line 2                                                           $3,228,271           Line 3

       Total current aggregate investment:
       (categorized by major line of energy-related business)
           Development and commercialization of photovoltaics (Category II)           9,542
           Production, conversion, sale and distribution of thermal energy
             products (Category VI)                                                  29,063
           Sale of technical, operational, management, and other services
             related to HVAC, refrigeration systems (Category VII)                    4,295
           Fuel transportation, handling and storage facilities (Category IX)            50
                                                                                  ---------

                Total current aggregate investment                                                    42,950           Line 4
                                                                                                   ---------

       Difference between the greater of $50 million or 15% of capitalization
           and the total aggregate investment of the registered holding company
            system (line 3 less line 4)                                                            3,185,321           Line 5
                                                                                                   ---------


Note:   The caption "Total average consolidated  capitalization" includes total common equity, preferred equity (including amounts
----    due within one year), long-term debt (including amounts due within one year) and short-term debt.

        The  caption  "Total  current  aggregate  investment"  includes  all  amounts  invested  or  committed  to be  invested in
        energy-related  companies on or after the date of  effectiveness of Rule 58 (March 24, 1997), or after  FirstEnergy  Corp.
        registered as a holding  company  (November 7, 2001) for which there is recourse,  directly or indirectly,  to FirstEnergy
        Corp. or any subsidiary company thereof. The amounts do not include purchase accounting adjustments.

    *   Total capitalization amounts for September 2002, December 2002 and March 2003 have been revised to reflect restatements in
        FirstEnergy's Amendment No. 2 of 2002 Form 10-K/A and Amendment No. 1 of March 2003 Form 10-Q.


                                                                 8






                                                    ITEM 5 - OTHER INVESTMENTS


                                               Aggregate Investment as of  Change in Investments
Major Line of Energy-Related Business                 June 30, 2003        During Reporting Period  Reason for Change in Investments
-------------------------------------          --------------------------  -----------------------  --------------------------------

                                                                                           
Energy management services (Category I)                $ 1,766 (1)                   -              No change.

Development and commercialization of                    34,322 (2)                 $3,140           In the third quarter of 2003,
electrotechnologies (Category II)                                                                   FirstEnergy through its direct
                                                                                                    subsidiary, GPU Diversified
                                                                                                    Holdings, LLC made $400 thousand
                                                                                                    investment to EnerTech Capital
                                                                                                    Partners II, LP. FirstEnergy
                                                                                                    also made $2,740 thousand
                                                                                                    capital contribution to
                                                                                                    PowerSpan Corp.

Energy services and retail energy sales                 18,158 (3)                   -              No change.
(Category V)

Production, conversion, sale and distribution           70,913 (4)                   -              No change.
of thermal energy products (Category VI)

Sale of technical, operational, management,            198,279 (5)                   -              No change.
and other services related to HVAC,
refrigeration systems (Category VII)

Fuel transportation, handling and storage                4,959 (6)                   -              No change.
facilities (Category IX)

Development and commercialization of                        46 (7)                   -              No change.
technologies that utilize coal waste
by-products (Category X)

(1)     Includes $1,766 that was invested in energy-related companies,  prior to FirstEnergy Corp. registered as a holding company
        (November 7, 2001).
(2)     Includes $27,920 that was invested in energy-related companies, prior to FirstEnergy Corp. registered as a holding company
        (November 7, 2001).
(3)     Includes $18,158 that was invested in energy-related companies, prior to FirstEnergy Corp. registered as a holding company
        (November 7, 2001).
(4)     Includes $41,850 that was invested in energy-related companies, prior to FirstEnergy Corp. registered as a holding company
        (November 7, 2001).
(5)     Includes  $193,984 that was invested in  energy-related  companies,  prior to  FirstEnergy  Corp.  registered as a holding
        company (November 7, 2001).
(6)     Includes $4,909 that was invested in energy-related companies,  prior to FirstEnergy Corp. registered as a holding company
        (November 7, 2001).
(7)     Includes $46 that was invested in energy-related  companies,  prior to FirstEnergy  Corp.  registered as a holding company
        (November 7, 2001).
                                                                 9




                   ITEM 6 - FINANCIAL STATEMENTS AND EXHIBITS


A.  Financial Statements
    --------------------

  A-1   Financial  statements of  FirstEnergy  Solutions  Corp.  for the quarter
        ended September 30, 2003.

  A-2   Financial  statements  of GPU  Diversified  Holdings LLC for the quarter
        ended September 30, 2003.

  A-3   Financial  statements  of Bay Shore Power  Company for the quarter ended
        September  30,  2003.  - filed  pursuant  to  request  for  confidential
        treatment.

  A-4   Financial  statements of Centerior Energy Services,  Inc for the quarter
        ended  September 30, 2003. - filed pursuant to request for  confidential
        treatment.

  A-5   Financial  statements of Warrenton River Terminal,  Ltd. for the quarter
        ended  September 30, 2003. - filed pursuant to request for  confidential
        treatment.

  A-6   Financial statements of Ancoma, Inc. for the quarter ended September 30,
        2003. - filed pursuant to request for confidential treatment.

  A-7   Financial  statements of Dunbar  Mechanical,  Inc. for the quarter ended
        September  30,  2003.  - filed  pursuant  to  request  for  confidential
        treatment.

  A-8   Financial  statements of Edwards  Electrical & Mechanical,  Inc. for the
        quarter  ended  September  30,  2003.  - filed  pursuant  to request for
        confidential treatment.

  A-9   Financial  statements of Elliot-Lewis  Corporation for the quarter ended
        September  30,  2003.  - filed  pursuant  to  request  for  confidential
        treatment.

  A-10  Financial  statements  of L.H.  Cranston and Sons,  Inc. for the quarter
        ended  September 30, 2003. - filed pursuant to request for  confidential
        treatment.

  A-11  Financial statements of Roth Bros., Inc. for the quarter ended September
        30, 2003. - filed pursuant to request for confidential treatment.

  A-12  Financial  statements  of The  Hattenbach  Company for the quarter ended
        September  30,  2003.  - filed  pursuant  to  request  for  confidential
        treatment.

  A-13  Financial  statements of R.P.C.  Mechanical,  Inc. for the quarter ended
        September  30,  2003.  - filed  pursuant  to  request  for  confidential
        treatment.


                                       10





ITEM 6 - FINANCIAL STATEMENTS AND EXHIBITS (Continued)


A. Financial Statements (Continued)
   --------------------------------

  A-14  Financial statements of Spectrum Controls Systems,  Inc. for the quarter
        ended  September 30, 2003. - filed pursuant to request for  confidential
        treatment.

  A-15  Financial  statements of GPU Solar, Inc. for the quarter ended September
        30, 2003. - filed pursuant to request for confidential treatment.


                                       11





             ITEM 6 - FINANCIAL STATEMENTS AND EXHIBITS (Continued)


B.  Exhibits

    Contracts Required by Item 3
    ----------------------------

   B-1      Stockholders Agreement made and entered into as of January 7, 1998
            by and among GPU International, Inc., AstroPower, Inc. and GPU
            Solar, Inc. (in connection with the sale of GPU International, Inc.
            on December 22, 2000, the Stockholders Agreement was amended such
            that GPU International, Inc. transferred its interest in GPU Solar,
            Inc. and its rights and responsibilities under the Stockholders
            Agreement to GPU Diversified Holdings LLC) - incorporated by
            reference to Exhibit B-12 to GPU's Quarterly Report on Form U-9C-3
            for the period ended December 31, 2000.

   B-2      Amendment No. 1 to Stockholders Agreement made and entered into as
            of December 1, 2000 by and among GPU International, Inc.,
            AstroPower, Inc., GPU Diversified Holdings LLC and GPU Solar, Inc.
            (this amendment essentially transferred GPU International, Inc.'s
            interest in GPU Solar, Inc. and its rights and responsibilities
            under the Stockholders Agreement to GPU Diversified Holdings LLC) -
            incorporated by reference to Exhibit B-13 to GPU's Quarterly Report
            on Form U-9C-3 for the period ended December 31, 2000.

   B-3      Contract between FirstEnergy Service Company and GPU Diversified
            Holdings LLC to provide legal and certain general and administrative
            services.

   B-4      Contract between FirstEnergy Service Company and FirstEnergy
            Solutions Corp. to provide legal and certain general and
            administrative services.

   Note:    Services rendered by Dunbar Mechanical, Inc. and Roth Bros., Inc.
   ----     to their associate companies are provided pursuant to purchase order
            contracts.


C. Certificate of FirstEnergy Corp.


                                       12




                                    SIGNATURE


        The  undersigned   registered  holding  company  has  duly  caused  this
quarterly report to be signed on its behalf by the undersigned officer thereunto
duly  authorized  pursuant to the  requirements  of the Public  Utility  Holding
Company Act of 1935.



                                                   FIRSTENERGY CORP.



November 26, 2003
                                  By:          /s/ Harvey L. Wagner
                                        -------------------------------------
                                                   Harvey L. Wagner
                                             Vice President, Controller
                                            and Chief Accounting Officer
                                            (Principal Accounting Officer)


                                       13