WASHINGTON, D.C. 20549

IN THE MATTER OF                                       CERTIFICATE
AMEREN CORPORATION                                     PURSUANT TO
                                                       RULE 24
File No. 70-10133

(Public Utility Holding Company Act of 1935)

     This Certificate of Notification pursuant to Rule 24 under the Public
Utility Holding Company Act of 1935, as amended (the "Act"), is filed by Ameren
Corporation ("Ameren"), a registered holding company, in connection with
Ameren's indirect acquisition of a membership interest in PowerTree Carbon
Company, LLC ("PowerTree"), a Delaware limited liability company, as authorized
by Order of the Securities and Exchange Commission (the "Commission") dated
November 10, 2003, in this proceeding (Holding Co. Act Release No. 27758).
Ameren hereby certifies to the Commission pursuant to Rule 24 that Ameren,
indirectly through its wholly-owned non-utility subsidiary, CIPSCO Investment
Company, has acquired a membership interest in PowerTree and made its initial
capital contribution to PowerTree.

     A "past tense" opinion of counsel is filed as Exhibit F hereto.


     Pursuant to the requirements of the Act, the undersigned company has duly
caused this document to be signed on its behalf by the undersigned thereunto
duly authorized.

                                         Ameren Corporation

                                         By: /s/ Steven R. Sullivan
                                         Name:   Steven R. Sullivan
                                         Title:  Senior Vice President
                                                 Policy, General Counsel, and

Dated: November 26, 2003