SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549



In the Matter of:                                 QUARTERLY CERTIFICATE PURSUANT
                                                  TO RULE 24 UNDER THE PUBLIC
AMEREN CORPORATION,                               UTILITY HOLDING COMPANY ACT OF
         and its Subsidiaries                     1935


File Nos.  70-10206, 70-9877, 70-10078, 70-10106, 70-10159


================================================================================

     Ameren Corporation  ("Ameren"),  a registered holding company, on behalf of
itself and its subsidiaries,  hereby files this certificate  pursuant to Rule 24
reporting on transactions  authorized by the Commission by orders dated June 18,
2004  (Holding  Co. Act Release No.  27860),  January 29, 2003  (Holding Co. Act
Release No.  27645),  February  27, 2003  (Holding  Co. Act Release No.  27655),
December  18,  2003  (Holding  Co. Act  Release  No.  27777) and October 5, 2001
(Holding Co. Act Release No. 27449).  This  certificate is filed with respect to
transactions consummated during the quarter ended June 30, 2004.


A.   Financing by Ameren
     -------------------
     (File Nos. 70-9877 and 70-10206 - Authorization  Period through June 30,
     2007):


     1.   Sales of any Common  Stock by Ameren  (other  than  pursuant  to Stock
          Plans) and the purchase price per share and the market price per share
          at the date of the agreement of sale.

          No such sales occurred during the 2nd quarter of 2004.


     2.   The total number of shares of Common  Stock  issued or issuable  under
          options,  warrants or other  stock-purchase  rights granted during the
          quarter under Stock Plans.

          Dividend Reinvestment and Stock Purchase Plan:        539,591
          Employee Long-Term Savings Plan 148 (401(k)):          34,227
            (Consisting of 3,180 original issue shares and
            31,047 shares purchased on the open market)
          Employee Long-Term Savings Plan 702 (401(k)):          19,565
            (Consisting of 3,751 original issue shares and
            15,814 shares purchased on the open market)
          Savings Investment Plan (401(k)):                     192,197
          Long Term Incentive Plan (Restricted Common Stock)          0
                                                                -------

          Total                                                 785,580
                                                                =======


     3.   If Common Stock has been  transferred  to a seller of  securities of a
          company being acquired,  the number of shares so issued, the value per
          share and whether the shares are restricted to the acquiror.

          N/A




     4.   The amount and terms of any Long-term Debt, Preferred Stock, Preferred
          Securities or Equity-linked  Securities issued by Ameren,  directly or
          indirectly through a Financing Subsidiary, during the quarter.

          N/A


     5.   The  amount  and  terms of any  Short-term  Debt  issued  directly  or
          indirectly by Ameren during the quarter.

          A.   There was no  commercial  paper issued  during the 2nd quarter of
               2004.

          B.   There were no bank loans during the 2nd quarter of 2004.

          Maximum indebtedness at any one time: $0.


     6.   A description of the amount, terms and purpose of any Guarantee issued
          during the quarter by Ameren and the name of the Subsidiary benefiting
          from such Guarantee.




          Parent                   Subsidiary                     Amount              Terms            Purpose
          -----                    ----------                     ------              -----            -------
                                                                      
          Ameren Corp.    Ameren Energy Fuels & Services Co.    $2,000,000      05/28/04-06/30/05   Credit Support
                            and CILCORP Energy Services, Inc.
          Ameren Corp.    Ameren Energy Marketing               $1,000,000      05/25/04-06/30/05   Credit Support
          Ameren Corp.    CILCORP Energy Services, Inc. and     $2,000,000      05/25/04-06/30/05   Credit Support
                            Ameren Energy Fuels & Services
          Ameren Corp.    Ameren Energy Marketing               $6,000,000      06/01/04-12/31/05   Credit Support
          Ameren Corp.    Ameren Energy Marketing               $5,000,000      05/13/04-12/31/04   Credit Support
          Ameren Corp.    Ameren Energy Marketing and           $2,000,000      04/15/04-03/31/05   Credit Support
                            CILCORP Energy Services, Inc.




     7.   The name and amount invested by Ameren, AmerenUE and AmerenCIPS in any
          Financing Subsidiary during the quarter.

          N/A


     8.   The notional  amount and principal terms of any Interest Rate Hedge or
          Anticipatory  Hedge  entered into by Ameren during the quarter and the
          identity of the parties to such instruments.

          No such agreements were entered into during the 2nd quarter of 2004.


     9.   Consolidated  balance sheet of Ameren,  AmerenUE and  AmerenCIPS as of
          the end of the calendar quarter.

          Incorporated  by reference  to  Quarterly  Report on Form 10-Q for the
          quarterly  period ended June 30, 2004 in File Nos.  1-14756  (Ameren),
          1-2967 (AmerenUE) and 1-3672 (AmerenCIPS).


B.   Financing by CILCORP and Utility Subsidiaries
     ---------------------------------------------
     (File Nos. 70-10106, 70-10078 - Authorization Period through March 31,
     2006):


     1.   The type of long-term securities (e.g., common stock,  long-term debt,
          preferred  securities,  etc.)  issued by  CILCORP  or AERG  during the
          quarter and the amount of consideration received.

          No such securities were issued during the 2nd quarter of 2004.

                                       2



     2.   The principal  terms (e.g.,  interest rate,  maturity,  dividend rate,
          sinking fund provisions,  etc.) of any long-term  securities issued by
          CILCORP or AERG during the quarter.

          N/A



     3.   The  amount  and  terms of any  Short-term  Debt  issued  by  CILCORP,
          AmerenUE, AmernCIPS, AmerenCILCO or AERG (other than to evidence Money
          Pool borrowings) during the quarter.

          No  Short-Term  Debt was issued  during the 2nd quarter of 2004 (other
          than through the Money Pool).



     4.   If payment of any debt  securities  may be  accelerated by the holders
          thereof by reason of a default by any associate  company of the issuer
          under  any  obligation  of  such  associate  company  (i.e.,  a  cross
          default),  the  identity of such  associate  company and the nature of
          obligation  of the  associate  company  to  which  the  cross  default
          relates.

          There exists a cross default  provision in the  indenture  relating to
          CILCORP's 8.70% and 9.375% senior unsecured notes, whereby an event of
          default would be triggered if there is a default in the payment of the
          principal  under any  mortgage,  indenture or  instrument  under which
          there may be issued or by which there may be secured or evidenced  any
          indebtedness for borrowed money of any significant subsidiary. Default
          must be for an aggregate  amount  exceeding  $25  million.  This would
          apply  to  any   outstanding   short-term  or  long-term   AmerenCILCO
          indebtedness, including funded bank loans.



     5.   The amount and purpose of any Guarantee issued by CILCORP.

          N/A



     6.   The notional  amount and principal terms of any Interest Rate Hedge or
          Anticipatory  Hedge  entered  into  during  the  quarter  by  CILCORP,
          AmerenUE,  AmerenCIPS,  AmerenCILCO  or AERG and the  identity  of the
          parties to such instruments.

          No such agreements were entered into during the 2nd quarter of 2004.



     7.   With  respect to each  Financing  Subsidiary  that has been  formed by
          CILCORP,  AmerenCILCO  or AERG, a  representation  that the  financial
          statements  of the parent  company of the Financing  Subsidiary  shall
          account for the  Financing  Subsidiary in  accordance  with  generally
          accepted accounting  principles and further, with respect to each such
          entity,  (i) the name of the  Financing  Subsidiary,  (ii) the  amount
          invested by the parent company in such Financing Subsidiary; (iii) the
          balance  sheet  account  where  the  investment  and  the  cost of the
          investment  are  booked;   (iv)  the  form  of   organization   (e.g.,
          corporation,  limited  partnership,  trust,  etc.)  of such  Financing
          Subsidiary;  (v) the percentage owned by the parent company;  and (vi)
          if any equity  interests  in the  Financing  Subsidiary  are sold in a
          non-public offering, the identity of the purchasers.

          N/A


     8.   Consolidated   balance  sheets  of  AmerenUE,   AmerenCIPS,   CILCORP,
          AmerenCILCO and AERG as of the end of the calendar quarter,  which may
          be  incorporated  by reference to filings,  if any, by such  companies
          under the Securities Act of 1933 or Securities Exchange Act of 1934.

          With the  exception  of AERG,  incorporated  by  reference to combined
          Quarterly  Report on Form 10-Q for the quarterly period ended June 30,
          2004 in File Nos.  1-2967  (AmerenUE),  1-3672  (AmerenCIPS),  2-95569
          (CILCORP), and 1-2732 (AmerenCILCO).  AERG's balance sheet to be filed
          confidentially under Rule 104 as Exhibit 1.0.

                                       3



     9.   Information  on each  sale or other  disposition  of a  Non-Retainable
          Interest during the calendar quarter.

          N/A



  
C.   Money Pool Transactions
     -----------------------
     (File Nos. 70-10106 - Authorization  Period through March 31, 2006):

     1.   The maximum outstanding amount of all borrowings from and loans to the
          Utility Money Pool by each Utility Money Pool  participant  during the
          quarter,  and the rate or range of rates charged on Utility Money Pool
          borrowings  and paid on  Utility  Money  Pool  investments  during the
          quarter.

          Maximum contribution/investment for AmerenCIPS - $0.0 million
          Maximum contribution/investment for AmerenUE - $0.0 million
          Maximum contribution/investment for AmerenCILCO - $0.0 million
          Maximum contribution/investment for AERG (lender only) - $0.0 million
          Maximum contribution/investment for Ameren Corporation (lender only) - $648.3 million
          Maximum contribution/investment for Ameren Services - $17.3 million

          Maximum borrowing for Ameren Services - $66.2 million
          Maximum borrowing for AmerenCIPS - $91.0 million
          Maximum borrowing for AmerenUE - $341.7 million
          Maximum borrowing for AmerenCILCO - $197.0 million

          Average interest rate for the Utility Money Pool for the quarter: 1.04%

     2.   The maximum outstanding amount of all borrowings from and loans to the
          Non-Regulated  Subsidiary Money Pool by each Non-Regulated  Subsidiary
          Money Pool  participant  during the quarter,  and the rate or range of
          rates charged on  Non-Regulated  Subsidiary  Money Pool borrowings and
          paid on Non- Regulated  Subsidiary Money Pool  investments  during the
          quarter.

          Maximum contribution/investment for Ameren Energy Marketing - $0.0 million
          Maximum contribution/investment for Union Electric Development - $1.9 million
          Maximum contribution/investment for CILCORP Energy Services - $5.1 million
          Maximum contribution/investment for CILCORP Investment Management - $5.3 million
          Maximum contribution/investment for CIPSCO Investment Co. - $2.3 million
          Maximum contribution/investment for Ameren Corporation - $436.3 million

          Maximum borrowing for Ameren Energy Fuels and Services - $30.3 million
          Maximum borrowing for Ameren Development - $1.4 million
          Maximum borrowing for Ameren Energy Communications - $29.4 million
          Maximum borrowing for Ameren Energy Development - $24.1 million
          Maximum borrowing for Ameren Energy Generating - $208.4 million
          Maximum borrowing for Ameren Energy Resources - $9.1 million
          Maximum borrowing for Ameren Energy - $9.9 million
          Maximum borrowing for CILCORP Energy Services - $0.0 million
          Maximum borrowing for Ameren ERC - $17.0 million
          Maximum borrowing for Illinois Materials Supply - $4.1 million
          Maximum borrowing for Ameren Energy Marketing - $58.4 million
          Maximum borrowing for Union Electric Development - $.4 million
          Maximum borrowing for CILCORP Ventures Inc. - $.3 million
          Maximum borrowing for AERG - $53.3 million
          Maximum borrowing for Medina Valley - $36.4 million
          Maximum borrowing for CIPSCO Investment Co. - $3.2 million
          Maximum borrowing for CILCORP Investment Management - $3.0 million

          Average interest rate for the Non-Regulated Subsidiary Money Pool for the quarter: 8.8%



                                       4




D.   Other Transactions Involving Ameren's Non-Utility Subsidiaries
     --------------------------------------------------------------
     (File No. 70-10159 - Authorization Period through December 31, 2006):

     1.   A copy of the balance  sheet and income  statement  for Ameren and its
          consolidated subsidiaries.

          Refer to Item A.9.


     2.   The amount and type of  investment in any Special  Purpose  Subsidiary
          during the quarter and a description of the  business(es)  of any such
          Special Purpose Subsidiary.

          N/A


     3.   The amounts and form of any guarantee or other form of credit  support
          provided by any  Non-Utility  Subsidiary  for the benefit of any other
          direct or indirect Non-Utility Subsidiary of Ameren.

          N/A


     4.   An  organizational  chart  showing,  as of the end of  such  quarterly
          period, all associate  companies of Ameren that identifies the type of
          each  Non-Utility   Subsidiary  (e.g.,  EWG,  FUCO  or  ETC,  Rule  58
          Subsidiary,  Intermediate  Subsidiary,  Financing Subsidiary,  Special
          Purpose  Subsidiary) and Ameren's  percentage equity ownership in each
          such Non-Utility Subsidiary.

          Organizational  chart to be filed in paper format as Exhibit 2.0 under
          Form SE.


     5.   A narrative description of Development  Activities during the quarter,
          the dollar amount expended on Development Activities,  and the type of
          potential investment (e.g., EWG, Rule 58 Subsidiary,  etc.) in respect
          of which such expenditures were made.

          N/A


     6.   A  description  of  non-utility   business  activities   conducted  by
          Non-Utility  Subsidiaries  (other than any Exempt Subsidiary)  outside
          the United States.

          N/A


     7.   A description  of the type and location of any  Energy-Related  Assets
          (or of the equity securities of any company owning such Energy-Related
          Assets)  acquired or constructed  during the quarter and the aggregate
          amount of expenditures thereon during the quarter.

          N/A


     8.   The notional amount, identity of counterparty,  and principal terms of
          any Anticipatory Hedge entered into by a Non-Utility Subsidiary during
          the quarter.

          No such agreements were entered into during the 2nd quarter of 2004.


     9.   With respect to any dividends paid by any  Non-Utility  Subsidiary out
          of capital or unearned surplus during the quarter, the date and amount
          thereof and the name of the entity to which such dividends were paid.

          On June 30, 2004,  a dividend in the amount of $18.2  million was paid
          out of capital from CILCORP Inc. to Ameren Corporation.

                                       5



     10.  A brief  description  of any internal  reorganization  of  Non-Utility
          Subsidiaries completed during the quarter and the purpose thereof.

          N/A


     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.

Ameren Corporation




By     /s/ Jerre E. Birdsong                     Date: August 26, 2004
  -----------------------------------
           Jerre E. Birdsong
           Vice President and Treasurer



                                       6




                                                                     Exhibit 3.0



                                   CERTIFICATE


     I certify that a copy of the foregoing was mailed via first class U.S. mail
on this  26th day of  August,  2004 to  Ameren  Corporation's  interested  state
commissions whose names and addresses are listed below.

     Mr. Robert Schallenberg
     Director - Utility Services Division
     Missouri Public Service Commission
     P.O. Box 360
     Jefferson City, MO 65102

     Ms. Mary Selvaggio, Director
     Financial Accounting Division
     Illinois Commerce Commission
     527 East Capitol Avenue
     Springfield, IL 62701

     Mr. Alan S. Pregozen
     CFA Finance Department
     Financial Analysis Division
     Illinois Commerce Commission
     527 East Capitol Avenue
     Springfield, IL 62701



     August 26, 2004                 AMEREN CORPORATION




                                     By:  /s/ Ronald K. Evans
                                        -----------------------------------
                                              Ronald K. Evans
                                              Managing Associate General Counsel
                                              Ameren Services Company
                                              1901 Chouteau Avenue
                                              P.O. Box 66149 (M/C 1310)
                                              St. Louis, Missouri 63166-6149
                                              (314) 554-2156
                                              (314) 554-4014 (fax)


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