Exhibit 5


                                          December 20, 2004


American Electric Power Company, Inc.
1 Riverside Plaza
Columbus, Ohio  43215

Ladies and Gentlemen:

      We have acted as counsel to American Electric Power Company, Inc., a New
York corporation (the "Company"), in connection with the Registration Statement
on Form S-3 (the "Registration Statement") filed by the Company with the
Securities and Exchange Commission (the "Commission") under the Securities Act
of 1933, as amended (the "Act"), relating to the issuance by the Company of an
aggregate of 20,000,000 shares of Common Stock, par value $6.50 per share
(together with any additional shares of such stock that may be issued by the
Company pursuant to Rule 462(b) (as prescribed by the Commission pursuant to the
Act) in connection with the transactions described in the Registration
Statement, the "Shares") pursuant to the Company's Dividend Reinvestment and
Direct Stock Purchase Plan (the "Plan").

      We have examined the Registration Statement and a form of the share
certificate and the Restated Certificate of Incorporation of the Company, which
has been filed with the Commission as an exhibit to the Registration Statement.
We also have examined the originals, or duplicates or certified or conformed
copies, of such corporate records, agreements, documents and other instruments
and have made such other investigations as we have deemed relevant and necessary
in connection with the opinions hereinafter set forth. As to questions of fact
material to this opinion, we have relied upon certificates or comparable
documents of public officials and of officers and representatives of the
Company.

      In rendering the opinion set forth below, we have assumed the genuineness
of all signatures, the legal capacity of natural persons, the authenticity of
all documents submitted to us as originals, the conformity to original documents
of all documents submitted to us as duplicates or certified or conformed copies
and the authenticity of the originals of such latter documents.

      Based upon the foregoing, and subject to the qualifications, assumptions
and limitations stated herein, we are of the opinion that (1) the Shares to be
acquired by participants in the Plan that are purchased in the open market or
from other participants have been validly issued and are fully paid and
nonassessable and (2) the Shares to be acquired by participants in the Plan that
are being issued by the Company, upon appropriate action being taken by the
Board of Directors or the Executive Committee of the Board of Directors of the
Company and upon the issuance and sale of such Shares in accordance with the
Plan and the payment of the purchase price therefor, will be validly issued,
fully paid and nonassessable.

      We do not express any opinion herein concerning any law other than the law
of the State of New York.

      We hereby consent to the filing of this opinion letter as Exhibit 5 to the
Registration Statement and to the use of our name under the caption "Validity of
Common Stock" in the Prospectus included in the Registration Statement.

                                    Very truly yours,

                                    /s/ Simpson Thacher & Bartlett LLP

                                    SIMPSON THACHER & BARTLETT LLP