as the Underwriters named in the Underwriting Agreement dated November 8, 2007 among the Underwriters and Public Service Company of Oklahoma November 14, 2007 Ladies and Gentlemen:

Exhibit
      5(a)
 
Citigroup
      Global Markets Inc.
Xxxxxxx
      Lynch, Pierce, Xxxxxx & Xxxxx
         Incorporated
Xxxxxx
      Xxxxxxx & Co. Incorporated
UBS
      Securities LLC
   as
      the Underwriters
   named
      in the Underwriting Agreement
   dated
      November 8, 2007 among the Underwriters and Public Service Company of
      Oklahoma

November
      14, 2007

Ladies
      and Gentlemen:

I
      am an
      employee of American Electric Power Service Corporation, an affiliate of Public
      Service Company of Oklahoma (the “Company”), and have acted as counsel to the
      Company in connection with the purchase by you (the “Underwriters”)
      of  $250,000,000 aggregate principal amount of 6.625% Senior Notes,
      Series G, due 2037 (the “Notes”), issued by the Company pursuant to the
      Underwriting Agreement, dated November 8, 2007 among the Company and the
      Underwriters (the “Underwriting Agreement”).

I
      have
      examined the Registration Statement on Form S-3 (File No. 333-133548) filed
      by
      the Company under the Securities Act of 1933, as amended (the “Securities Act”),
      as it became effective under the Securities Act (the “Registration Statement”),
      and the Company’s prospectus, dated May 4, 2006 (the “Basic Prospectus”), as
      supplemented by a preliminary prospectus supplement dated November 8, 2007,
      including all documents incorporated by reference therein (the Basic Prospectus
      as so supplemented, the “Preliminary Prospectus”) and a prospectus supplement,
      dated November 8, 2007 (the “Prospectus Supplement”, and together with the Basic
      Prospectus, the “Prospectus”), filed by the Company pursuant to Rule 424(b) of
      the rules and regulations of the Securities and Exchange Commission (the
“Commission”) under the Securities Act, which, pursuant to Form S-3,
      incorporates by reference or is deemed to incorporate by reference the Annual
      Report on Form 10-K of the Company for the fiscal year ended December 31, 2006,
      (the “Form 10-K”), and the Quarterly Reports on Form 10-Q of the Company for the
      quarters ended March 31, 2007, June 30, 2007 and September 30, 2007
      (collectively, the “Exchange Act Documents”), each as filed under the Securities
      Exchange Act of 1934, as amended (the “Exchange Act”).

I
      have
      also examined the free writing prospectus prepared by the Company (the
“Permitted Free Writing Prospectus”) and filed under Rule 433 of the Securities
      Act.  The documents listed in Exhibit 3 to the Underwriting Agreement
      taken together, are collectively referred to as the “Pricing Disclosure
      Package”.   In addition, I also have examined (i) the Indenture,
      dated as of November 1, 2000, between the Company and The Bank of New York,
      as
      Trustee (the “Trustee”), as previously supplemented (the “Original Indenture”)
      and as to be further supplemented by a Seventh Supplemental Indenture, dated
      as
      of November 14, 2007 (the “Supplemental Indenture”; the Original Indenture as
      supplemented by the Supplemental Indenture, the “Indenture”); (ii) the
      Underwriting Agreement; and (iii) a duplicate of the global note representing
      the Notes.  In addition, I have examined, and have relied as to
      matters of fact upon, the documents delivered to you at closing, and upon
      originals or copies, certified or otherwise identified to my satisfaction,
      of
      such corporate records, agreements, documents and other instruments and such
      certificates or comparable documents or oral statements of public officials
      and
      of officers and representatives of the Company, and have made such other and
      further investigations as I have deemed relevant and necessary as a basis for
      the opinions hereinafter set forth.

In
      such
      examination, I have assumed the genuineness of all signatures, the legal
      capacity of natural persons, the authenticity of all documents submitted to
      me
      as originals, the conformity to original documents of all documents submitted
      to
      me as certified or photostatic copies, and the authenticity of the originals
      of
      such latter documents.

In
      furnishing this opinion, with your permission, I have assumed that (i) the
      Indenture and the Notes have been duly authorized, executed and delivered (and
      in the case of the Notes, authenticated) by the Trustee; (ii) the Trustee has
      the power and authority to execute, authenticate, deliver and perform the
      Indenture and the Notes; (iii) the execution, authorization, delivery and
      performance of the Indenture and the Notes by the Trustee fully comply in all
      material respects with all laws, rules, regulations, judgments and orders
      applicable to the Trustee and its property; and (iv) the Indenture constitutes
      the valid and legally binding obligation of the Trustee.

Based
      on
      the foregoing, and subject to the qualifications, assumptions and limitations
      stated herein, I am of the opinion that:


      

          
            (a)

            The
                Company is a corporation duly organized and existing under the laws
                of the
                State of Oklahoma, is duly qualified to do business as a foreign
                corporation under the laws of the State of Texas and has due corporate
                authority to carry on the public utility business in which it is
                engaged
                and to own and operate the properties used by it in such
                business.

          

    

      

          
            (b)

            The
                Indenture has been duly qualified under the Trust Indenture Act of
                1939,
                as amended.

          

    

      

          
            (c)

            The
                Company has full power and authority to execute and deliver the Indenture,
                and the Indenture has been duly authorized, executed and delivered
                by the
                Company and constitutes a valid and legally binding obligation of
                the
                Company enforceable against the Company in accordance with its
                terms.  The Underwriting Agreement has been duly authorized,
                executed and delivered by the
                Company.

          

    

      

          
            (d)

            The
                Company has full power and authority to execute and deliver the Notes,
                the
                Notes have been duly authorized, executed and delivered by the Company,
                and, upon payment and delivery in accordance with the Underwriting
                Agreement, constitute valid and legally binding obligations of the
                Company
                enforceable against the Company in accordance with their terms and
                entitled to the benefits of the
                Indenture.

          

    

      

          
            (e)

            The
                Corporation Commission of the State of Oklahoma has issued an appropriate
                order authorizing, among other things, the issuance and the sale
                of the
                Notes; such order is sufficient for the issuance and the sale of
                the
                Notes; and the issuance and the sale of the Notes in accordance with
                the
                Underwriting Agreement are in conformity with the terms of such
                order.  The Commission has issued an appropriate order under the
                Securities Act with respect to the sale of the Notes.  No other
                approval or consent of any governmental body is required for the
                issuance
                and the sale of the Notes to you or the performance by the Company
                of its
                obligations under the Underwriting Agreement or the
                Indenture.  I have not considered whether any approval or
                consent is required under the “blue sky” laws of any
                jurisdiction.

          

    

      

          
            (f)

            The
                statements made in the Prospectus under the captions “Description of the
                Notes” and “Supplemental Description of the Senior Notes”, insofar as they
                purport to constitute summaries of certain terms of documents referred
                to
                therein, constitute accurate summaries of the terms of such documents
                in
                all material respects.

          

    

My
      opinions set forth in paragraphs (c) and (d) above are subject to (1) the
      effects of bankruptcy, insolvency, fraudulent conveyance, reorganization,
      moratorium and other similar laws relating to or affecting creditors’ rights
      generally; (2) general equitable principles (whether considered in a proceeding
      in equity or at law); and (3) an implied covenant of good faith and fair
      dealing.

I
      have
      not independently verified the accuracy, completeness or fairness of the
      statements made in the Registration Statement, the Prospectus, the Permitted
      Free Writing Prospectus or the Exchange Act Documents, and I take no
      responsibility therefore, except as and to the extent set forth in paragraph
      (f)
      above.  In connection with, and under the circumstances applicable to
      the offering of the Notes, I participated in conferences with certain officers
      and employees of the Company, with representatives of Deloitte & Touche LLP,
      with your representatives and with your counsel in the course of the preparation
      by the Company of the Registration Statement,  the Permitted Free
      Writing Prospectus and the Prospectus (including the Exchange Act Documents)
      and
      also reviewed certain records and documents furnished to me by the Company,
      as
      well as documents delivered to you at closing.  I did not prepare the
      Exchange Act Documents; however, I reviewed the Exchange Act Documents prior
      to
      their filing with the Commission.

Based
      upon my review of the Registration Statement, the Prospectus, the Permitted
      Free
      Writing Prospectus and the Exchange Act Documents, my reviews made in connection
      with the preparation of the Registration Statement and the Prospectus, my
      participation in the conferences referred to above, my review of the records
      and
      documents as described above, as well as my understanding of the U.S. federal
      securities laws and the experience I have gained in my practice thereunder,
      (i)
      I advise you that each of the Registration Statement on the date of the
      Underwriting Agreement, and the Preliminary Prospectus, the Permitted Free
      Writing Prospectus and the Prospectus, as of their respective
      dates,  appeared on its face to be appropriately responsive, in all
      material respects, to the requirements of the Securities Act and the applicable
      rules and regulations of the Commission thereunder, except that in each case
      I
      express no view with respect to the financial statements or other financial
      or
      statistical data contained in, incorporated or deemed incorporated by reference
      in, or omitted from such documents, and (ii) nothing has come to my attention
      that causes me to believe that the Registration Statement on the date of the
      Underwriting Agreement  (including the Exchange Act Documents on file
      with the Commission as of such date), contained any untrue statement of a
      material fact or omitted to state any material fact required to be stated
      therein or necessary in order to make the statements therein not misleading,
      or
      that the Pricing Disclosure Package, as of the Applicable Time (as defined
      in
      the Underwriting Agreement), included an untrue statement of a material fact
      or
      omitted to state a material fact necessary in order to make the statements
      therein, in light of the circumstances under which they were made not
      misleading, or that the Prospectus (including the Exchange Act Documents),
      as of
      its date or as of the date hereof, contained or contains any untrue statement
      of
      a material fact or omitted or omits to state any material fact necessary in
      order to make the statements therein, in light of the circumstances under which
      they were made, not misleading, except that in each case I express no belief
      with respect to the financial statements or other financial or statistical
      data
      contained in, incorporated or deemed incorporated by reference in, or omitted
      from the Registration Statement, the Prospectus or the Exchange Act
      Documents.

I
      am
      today delivering an executed copy of this opinion to the Trustee and Xxxxx
&
XxXxxxx LLP, who are entitled to rely upon this opinion to the same extent
      as if
      such opinion were addressed to them.  This opinion is rendered to you,
      the Trustee and Xxxxx & XxXxxxx LLP, in connection with the above-described
      transaction.  This opinion may not be relied upon by you, the Trustee
      or Xxxxx & XxXxxxx LLP for any other purpose, or relied upon or furnished to
      any other person, firm or corporation without my prior written
      permission.

Very
      truly yours,

/s/
      Xxxxxx X. Xxxxxxxxxx
Xxxxxx
      X.
      Xxxxxxxxxx
Document Metadata

as the Underwriters named in the Underwriting Agreement dated November 8, 2007 among the Underwriters and Public Service Company of Oklahoma November 14, 2007 Ladies and Gentlemen:

Document Metadata
