Exhibit 32.7


                           SECTION 1350 CERTIFICATION
                        OF PRINCIPAL EXECUTIVE OFFICER OF
                        AMEREN ENERGY GENERATING COMPANY
                         (required by Section 906 of the
                           Sarbanes-Oxley Act of 2002)


In connection  with the report on Form 10-Q for the quarterly  period ended June
30, 2004 of Ameren Energy  Generating  Company (the "Company") as filed with the
Securities  and Exchange  Commission  on the date hereof (the "Form  10-Q"),  I,
Thomas R. Voss, chief executive officer of the Company,  certify, pursuant to 18
U.S.C. ss.1350, as adopted pursuant to ss.906 of the Sarbanes-Oxley Act of 2002,
that:

(1)  The Form 10-Q fully  complies  with the  requirements  of Section  13(a) or
     15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

(2)  The information contained in the Form 10-Q fairly presents, in all material
     respects, the financial condition and results of operations of the Company.


Dated: August 9, 2004



                                           /s/ Thomas R. Voss
                                           ---------------------------------
                                           Thomas R. Voss
                                           President
                                           (Principal Executive Officer)