Document:

PSO Fifth Supplemental Indenture 05/20/05, Series E

    
      

    

    EXHIBIT
      4(c)

    

     

     

    

    

    

    PUBLIC
      SERVICE COMPANY OF OKLAHOMA

    

    and

    

    THE
      BANK
      OF NEW YORK,

    AS
      TRUSTEE

    

    ___________________

    

    

    FIFTH
      SUPPLEMENTAL INDENTURE

    

    Dated
      as
      of May 20, 2005

    

    

    Supplemental
      to the Indenture

    dated
      as
      of November 1, 2000

    

    

    4.70%
      Senior Notes, Series E, due 2011

    

     

    
      
        

      

     

    FIFTH
      SUPPLEMENTAL INDENTURE, dated as of May 20, 2005, between PUBLIC SERVICE COMPANY
      OF OKLAHOMA, a corporation duly organized and existing under the laws of the
      State of Oklahoma (the “Company”), and THE BANK OF NEW YORK, a New York banking
      corporation organized and existing under the laws of the State of New York,
      as
      Trustee under the Original Indenture referred to below (the “Trustee”).

    

    RECITALS
      OF THE COMPANY

    

    The
      Company has heretofore executed and delivered to the Trustee an indenture dated
      as of November 1, 2000 (the “Original Indenture”), to provide for the issuance
      from time to time of its debentures, notes or other evidences of indebtedness
      (the “Senior Notes”), the form and terms of which are to be established as set
      forth in Section 201 and 301 of the Original Indenture.

    

    Section
      901 of the Original Indenture provides, among other things, that the Company
      and
      the Trustee may enter into indentures supplemental to the Original Indenture
      for, among other things, the purpose of establishing the form and terms of
      the
      Senior Notes of any series as permitted in Sections 201 and 301 of the Original
      Indenture.

    

    The
      Company desires to create a series of the Senior Notes in an aggregate principal
      amount of $75,000,000 to be designated the “4.70% Senior Notes, Series E, due
      2011” (the “4.70% Senior Notes”), and all action on the part of the Company
      necessary to authorize the issuance of the 4.70% Senior Notes under the Original
      Indenture and this Fifth Supplemental Indenture has been duly
      taken.

    

    All
      acts
      and things necessary to make the 4.70% Senior Notes, when executed by the
      Company and completed, authenticated and delivered by the Trustee as provided
      in
      the Original Indenture and this Fifth Supplemental Indenture, the valid and
      binding obligations of the Company and to constitute these presents a valid
      and
      binding supplemental indenture and agreement according to its terms, have been
      done and performed.

    

    NOW,
      THEREFORE, THIS FIFTH SUPPLEMENTAL INDENTURE WITNESSETH:

    

    That
      in
      consideration of the premises and of the acceptance and purchase of the 4.70%
      Senior Notes by the Holders thereof and of the acceptance of this trust by
      the
      Trustee, the Company covenants and agrees with the Trustee, for the equal
      benefit of the Holders of the 4.70% Senior Notes, as follows: 

    

    ARTICLE
      ONE

    Definitions

    

    The
      use
      of the terms and expressions herein is in accordance with the definitions,
      uses
      and constructions contained in the Original Indenture and the form of the Global
      Security attached hereto as Exhibit
      A.

    

    

    ARTICLE
      TWO

    Terms
      and
      Issuance of the 4.70% Senior Notes

    

    SECTION
      201.     Issue
      of 4.70% Senior Notes

    

    A
      series
      of Senior Notes which shall be designated the “4.70% Senior Notes, Series E, due
      2011” shall be executed, authenticated and delivered from time to time in
      accordance with the provisions of, and shall in all respects be subject to,
      the
      terms, conditions and covenants of, the Original Indenture and this Fifth
      Supplemental Indenture (including the form of Global Security set forth in
      Exhibit
      A
      hereto).
      The aggregate principal amount of the 4.70% Senior Notes, which may be
      authenticated and delivered under this Fifth Supplemental Indenture shall
      initially be $75,000,000, and such principal amount of the 4.70% Senior Notes
      may be increased from time to time. All 4.70% Senior Notes need not be issued
      at
      the same time and such series may be reopened at any time, without the consent
      of any Holder, for issuance of additional 4.70% Senior Notes. Any such
      additional 4.70% Senior Notes will have the same interest rate, maturity and
      other terms as those initially issued.

    

    SECTION
      202.     Form
      of 4.70% Senior Notes, Incorporation of Terms

    

    The
      4.70%
      Senior Notes shall be substantially in the form of the Global Security attached
      hereto as Exhibit
      A.
      The
      terms of such 4.70% Senior Notes are herein incorporated by reference and are
      part of this Fifth Supplemental Indenture.

    

    SECTION
      203.     Depositary
      for Global Securities

    

    The
      Depositary for any Global Securities of the series of which this 4.70% Senior
      Note is a part shall be The Depository Trust Company in The City of New
      York.

    

    SECTION
      204.     Restrictions
      on Liens

    

    The
      covenant contained in Section 1007 of the Original Indenture shall not be
      applicable to the 4.70% Senior Notes.

    

    So
      long
      as any of the 4.70% Senior Notes are outstanding, the Company will not create
      or
      suffer to be created or to exist any additional mortgage, pledge, security
      interest, or other lien (collectively “Liens”) on any of its utility properties
      or tangible assets now owned or hereafter acquired to secure any indebtedness
      for borrowed money (“Secured Debt”), without providing that the 4.70% Senior
      Notes will be similarly secured. This restriction does not apply to the
      Company’s subsidiaries, nor will it prevent any of them from creating or
      permitting to exist Liens on their property or assets to secure any Secured
      Debt. Further, this restriction on Secured Debt does not apply to the Company’s
      existing first mortgage bonds that have previously been issued under its
      Mortgage and Deed of Trust, dated July 1, 1945, between the Company and Liberty
      Bank and Trust Company of Tulsa, National Association, as successor to The
      First
      National Bank and Trust Company of Tulsa, now The Bank of New York, as successor
      Trustee or any indenture supplemental thereto; provided that this restriction
      will apply to future issuances thereunder (other than issuances of refunding
      first mortgage bonds). In addition, this restriction does not prevent the
      creation or existence of:

    

    
      	 	
              (a)

            	
              Liens
                on property existing at the time of acquisition or construction of
                such
                property (or created within one year after completion of such acquisition
                or construction), whether by purchase, merger, construction or otherwise,
                or to secure the payment of all or any part of the purchase price
                or
                construction cost thereof, including the extension of any Liens to
                repairs, renewals, replacements, substitutions, betterments, additions,
                extensions and improvements then or thereafter made on the property
                subject thereto;

            
	 	 	 
	 	
              (b)

            	
              Financing
                of the Company’s accounts receivable for electric
                service;

            
	 	 	 
	 	
              (c)

            	
              Any
                extensions, renewals or replacements (or successive extensions, renewals
                or replacements), in whole or in part, of liens permitted by the
                foregoing
                clauses; and

            
	 	 	 
	 	
              (d)

            	
              The
                pledge of any bonds or other securities at any time issued under
                any of
                the Secured Debt permitted by the above
                clauses.

            

    

    

    In
      addition to the permitted issuances above, Secured Debt not otherwise so
      permitted may be issued in an amount that does not exceed 15% of Net Tangible
      Assets as defined below. 

    

    “Net
      Tangible Assets” means the total of all assets (including revaluations thereof
      as a result of commercial appraisals, price level restatement or otherwise)
      appearing on the Company’s balance sheet, net of applicable reserves and
      deductions, but excluding goodwill, trade names, trademarks, patents,
      unamortized debt discount and all other like intangible assets (which term
      shall
      not be construed to include such revaluations), less the aggregate of the
      Company’s current liabilities appearing on such balance sheet. For purposes of
      this definition, the Company’s balance sheet does not include assets and
      liabilities of its subsidiaries.

    

    This
      restriction also does not apply to or prevent the creation or existence of
      leases made, or existing on property acquired, in the ordinary course of
      business.

    

    SECTION
      205.     Place
      of Payment

    

    The
      Place
      of Payment in respect of the 4.70% Senior Notes will be at the principal office
      or place of business of the Trustee or its successor in trust under the
      Indenture, which, at the date hereof, is located at 101 Barclay Street, New
      York, NY 10281, Attention: Corporate Trust Department.

    

    SECTION
      206.     Sinking
      Funds.

    

    Article
      Twelve of the Indenture shall not apply to the 4.70% Senior Notes.

    

    SECTION
      207.    Redemption

    

    The
      4.70%
      Senior Notes shall be redeemable at the option of the Company, in whole at
      any
      time or in part from time to time, upon not less than thirty but not more than
      sixty days’ previous notice given by mail to the registered owners of the 4.70%
      Senior Notes at a redemption price equal to the greater of (i) 100% of the
      principal amount of the 4.70% Senior Notes being redeemed and (ii) the sum
      of
      the present values of the remaining scheduled payments of principal and interest
      on the 4.70% Senior Notes being redeemed (excluding the portion of any such
      interest accrued to the date of redemption) discounted (for purposes of
      determining present value) to the redemption date on a semi-annual basis
      (assuming a 360-day year consisting of twelve 30-day months) at the Treasury
      Rate (as defined below) plus 15 basis points, plus, in each case, accrued
      interest thereon to the date of redemption.

    

    “Comparable
      Treasury Issue” means the United States Treasury security selected by an
      Independent Investment Banker as having a maturity comparable to the remaining
      term of the 4.70%
      Senior Notes
      that would be utilized, at the time of selection and in accordance with
      customary financial practice, in pricing new issues of corporate debt securities
      of comparable maturity to the remaining term of the 4.70% Senior
      Notes.

    

    “Comparable
      Treasury Price” means, with respect to any redemption date, (1) the average of
      the Reference Treasury Dealer Quotations for such redemption date after
      excluding the highest and lowest such Reference Treasury Dealer Quotations,
      or
      (2) if fewer than four such Reference Treasury Dealer Quotations are obtained,
      the average of all such quotations.

    

    “Independent
      Investment Banker” means one of the Reference Treasury Dealers appointed by the
      Company and reasonably acceptable to the Trustee.

    

    “Reference
      Treasury Dealer” means a primary U.S. government securities dealer in New York
      City selected by the Company and reasonably acceptable to the
      Trustee.

    

    “Reference
      Treasury Dealer Quotation” means, with respect to each Reference Treasury Dealer
      and any redemption date, the average, as determined by the Trustee, of the
      bid
      and asked prices for the Comparable Treasury Issue (expressed in each case
      as a
      percentage of its principal amount) quoted in writing to the Trustee by such
      Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the
      third Business Day preceding such redemption date.

    

    “Treasury
      Rate” means, with respect to any redemption date, the rate per annum equal to
      the semi-annual equivalent yield to maturity of the Comparable Treasury Issue,
      assuming a price for the Comparable Treasury Issue (expressed as a percentage
      of
      its principal amount) equal to the Comparable Treasury Price for such redemption
      date.

     

    ARTICLE
      THREE

     

    Miscellaneous

    

    SECTION
      301.     Execution
      as Supplemental Indenture

    

    This
      Fifth Supplemental Indenture is executed and shall be construed as an indenture
      supplemental to the Original Indenture and, as provided in the Original
      Indenture, this Fifth Supplemental Indenture forms a part thereof.

    

    SECTION
      302.     Conflict
      with Trust Indenture Act

    

    If
      any
      provision hereof limits, qualifies or conflicts with another provision hereof
      which is required to be included in this Fifth Supplemental Indenture by any
      of
      the provisions of the Trust Indenture Act, such required provision shall
      control. 

    

    SECTION
      303.    Effect
      of Headings

    

    The
      Article and Section headings herein are for convenience only and shall not
      affect the construction hereof.

    

    SECTION
      304.     Successors
      and Assigns

    

    All
      covenants and agreements by the Company in this Fifth Supplemental Indenture
      shall bind its successors and assigns, whether so expressed or not.

    

    SECTION
      305.     Separability
      Clause

    

    In
      case
      any provision in this Fifth Supplemental Indenture or in the 4.70% Senior Notes
      shall be invalid, illegal or unenforceable, the validity, legality and
      enforceability of the remaining provisions shall not in any way be affected
      or
      impaired thereby.

    

    SECTION
      306.     Benefits
      of Fifth Supplemental Indenture

    

    Nothing
      in this Fifth Supplemental Indenture or in the 4.70% Senior Notes, express
      or
      implied, shall give to any Person, other than the parties hereto and their
      successors hereunder and the Holders, any benefit or any legal or equitable
      right, remedy or claim under this Fifth Supplemental Indenture.

    

    SECTION
      307.     Execution
      and Counterparts

    

    This
      Fifth Supplemental Indenture may be executed in any number of counterparts,
      each
      of which shall be deemed to be an original, but all such counterparts shall
      together constitute but one and the same instrument.

    

    IN
      WITNESS WHEREOF, the parties hereto have caused this Fifth Supplemental
      Indenture to be duly executed and attested, all as of the day and year first
      above written. 

    

    

    
      	 	
              PUBLIC
                SERVICE COMPANY OF OKLAHOMA

            
	 	 	 
	 	
              By:

            	
              /s/
                Stephan T. Haynes

            
	 	 	
              Assistant
                Treasurer

            
	
              Attest:

            	 	 
	
              /s/
                Thomas G. Berkemeyer

            	 	 
	
              Assistant
                Secretary

            	 	 
	 	 	
              THE
                BANK OF NEW YORK,

            
	 	 	
              as
                Trustee

            
	 	 	 
	 	
              By:

            	
              /s/
                Van K. Brown

            
	 	 	
              Authorized
                Signatory

            
	
              Attest:

            	 	 
	
              /s/
                Remo J. Reale

            	 	 
	
              Name: Remo
                J. Reale

            	 	 
	
              Title: Vice
                President

            	 	 

    

    

    
      	
              STATE
                OF OHIO

            	
              )

            	 
	 	
              )

            	
              :
                ss

            
	
              COUNTY
                OF FRANKLIN

            	
              )

            	 

    

    

    On
      the
      5th day of May, 2005, personally appeared before me, a Notary Public within
      and
      for said County in the State of Ohio, Stephan T. Haynes and Thomas G.
      Berkemeyer, to me known and known to me to be respectively an Assistant
      Treasurer and an Assistant Secretary of Public Service Company of Oklahoma,
      one
      of the corporations named in and which executed the foregoing instrument, who
      severally acknowledged that they did sign said instrument as such Assistant
      Treasurer and Assistant Secretary for and on behalf of said corporation and
      that
      the same is their free act and deed as such Assistant Treasurer and Assistant
      Secretary, respectively, and the free and corporate act and deed of said
      corporation. 

    

    In
      witness whereof, I have hereunto set my hand notarial seal this 19th day of
      May,
      2005.

    

    
      	 	
              /s/
                Ann B. Graf

            
	 	
              Notary
                Public, State of Ohio

              Attorney
                at Law

              No
                Expiration Date

            

    

     

    

    
      	
              STATE
                OF NEW YORK

            	
              )

            	 
	 	
              )

            	
              :
                ss

            
	
              COUNTY
                OF NEW YORK

            	
              )

            	 

    

    

    On
      the
      20th day of May, 2005, personally appeared before me, a Notary Public within
      and
      for said County in the State of New York, Van K. Brown and Remo J. Reale, to
      me
      known and known to me to be respectively the Vice President and Vice President
      of The Bank of New York, one of the corporations named in and which executed
      the
      foregoing instrument, who severally acknowledged that they did sign said
      instrument as such Vice President and Vice President for and on behalf of said
      corporation and that the same is their free act and deed as such Vice President
      and Vice President, respectively, and the free and corporate act and deed of
      said corporation. 

    

    In
      witness whereof, I have hereunto set my hand notarial seal this 20th day of
      May,
      2005.

    

    
      	 	
              /s/
                William J. Casssels

            
	 	
              Notary
                Public, State of New York

              Expires
                May 18, 2006

            

    

    

     

    
      

    

    EXHIBIT
      A
      TO EXHIBIT 4(c)

    

    THIS
      SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER
      REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE OF A
      DEPOSITARY. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE
      NAME
      OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED
      CIRCUMSTANCES DESCRIBED IN THE INDENTURE, AND NO TRANSFER OF THIS SECURITY
      (OTHER THAN A TRANSFER OF THIS SECURITY AS A WHOLE BY THE DEPOSITARY TO A
      NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY
      OR
      ANOTHER NOMINEE OF THE DEPOSITARY) MAY BE REGISTERED EXCEPT IN LIMITED
      CIRCUMSTANCES. 

    

    Unless
      this certificate is presented by an authorized representative of The Depository
      Trust Company, a New York corporation (“DTC”), to Public Service Company of
      Oklahoma or its agent for registration of transfer, exchange or payment, and
      any
      definitive certificate issued is registered in the name of Cede & Co. or in
      such other name as is requested by an authorized representative of DTC (and
      any
      payment is made to Cede & Co. or to such other entity as is requested by an
      authorized representative of DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF
      FOR
      VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL in as much as the registered
      owner hereof, Cede & Co., has an interest herein.

    

    No.
      R-1

    

    PUBLIC
      SERVICE COMPANY OF OKLAHOMA

    4.70%
      Senior Notes, Series E, due 2011

    

    
      	
              CUSIP
                No. 744533
                BG 4

            	
              $75,000,000

            

    

    

    PUBLIC
      SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under
      the
      laws of the State of Oklahoma (the “Company”, which term includes any successor
      Person under the Indenture hereinafter referred to), for value received, hereby
      promises to pay to CEDE & CO. or registered assigns, the principal sum of
SEVENTY-FIVE
      MILLION DOLLARS
      ($75,000,000) on May 15, 2011 (the “Final Maturity”), and to pay interest
      thereon from May 20, 2005 or from the most recent Interest Payment Date to
      which
      interest has been paid or duly provided for, semi-annually on May 15 and
      November 15 each year, commencing November 15, 2005, at the interest rate per
      annum specified above, until the principal amount shall have been paid or duly
      provided for. Interest shall be computed on the basis of a 360-day year of
      twelve 30-day months.

    

    The
      interest so payable, and punctually paid or duly provided for, on any Interest
      Payment Date will, as provided in such Indenture, be paid to the Person in
      whose
      name this Security (or one or more Predecessor Securities) is registered at
      the
      close of business on the Regular Record Date for such interest, which shall
      be
      the April 30 or October 31 (whether or not a Business Day) immediately preceding
      the Interest Payment Date. Any such interest not so punctually paid or duly
      provided for will forthwith cease to be payable to the Holder on such Regular
      Record Date and may either be paid to the Person in whose name this Security
      (or
      one or more Predecessor Securities) is registered at the close of business
      on a
      Special Record Date for the payment of such Defaulted Interest to be fixed
      by
      the Trustee, notice whereof shall be given to Holders of Securities of this
      series not less than 10 days prior to such Special Record Date, or be paid
      at
      any time in any other lawful manner not inconsistent with the requirements
      of
      any securities exchange on which the Securities of this series may be listed,
      and upon such notice as may be required by such exchange, all as more fully
      provided in said Indenture.

    

    Payment
      of the principal of (and premium, if any) and interest on this Security will
      be
      made at the office or agency of the Company maintained for that purpose in
      the
      Borough of Manhattan, The City of New York, New York, in such coin or currency
      of the United States of America as at the time of payment is legal tender for
      the payment of public and private debts; provided, however, that at the option
      of the Company payment of interest may be made by check mailed to the address
      of
      the Person entitled thereto as such address shall appear in the Security
      Register.

    

    This
      Security has initially been issued in the form of a Global Security, and the
      Company has initially designated The Depository Trust Company (the “Depositary”,
      which term shall include any successor depositary) as the depositary for this
      Security. For as long as this Security or any portion hereof is issued in such
      form, and notwithstanding the previous paragraph, all payments of interest,
      principal and other amounts in respect of this Security or portion thereof
      shall
      be made to the Depositary or its nominee in accordance with the Applicable
      Procedures in the coin or currency specified above and as further provided
      herein.

    

    This
      Security is one of a duly authorized issue of securities of the Company (the
      “Securities”), issued and to be issued in one or more series under an Indenture,
      dated as of November 1, 2000, as amended and supplemented from time to time
      (the
“Indenture”, which term shall have the meaning assigned to it in such
      instrument), between the Company and The Bank of New York, a New York banking
      corporation, as Trustee (the “Trustee”, which term includes any successor
      trustee under the Indenture), as to which Indenture and all indentures
      supplemental thereto reference is hereby made for a statement of the respective
      rights, limitations of rights, duties and immunities thereunder of the Company,
      the Trustee and the Holders and of the terms upon which the Securities are,
      and
      are to be, authenticated and delivered. This Security is one of the series
      designated on the face hereof, limited in aggregate principal amount to
      $75,000,000; provided, however, the aggregate principal amount hereof can be
      increased, without the consent of the Holder, as permitted by the provisions
      of
      the Original Indenture. The provisions of this Security, together with the
      provisions of the Indenture, shall govern the rights, obligations, duties and
      immunities of the Holder, the Company and the Trustee with respect to this
      Security, provided that, if any provision of this Security necessarily conflicts
      with any provision of the Indenture, the provision of this Security shall be
      controlling to the fullest extent permitted under the Indenture.

    

    The
      Securities of this Series are subject to redemption upon not less than 30 nor
      more than 60 days’ notice by mail to the Holders of such Securities at their
      addresses in the Security Register for such Series at the option of the Company,
      in whole or in part, from time to time at a Redemption Price equal to
the
      greater of (i) 100% of the principal amount of the Securities being redeemed
      and
      (ii) the sum of the present values of the remaining scheduled payments of
      principal and interest on the Securities being redeemed (excluding the portion
      of any such interest accrued to the date of redemption) discounted (for purposes
      of determining present value) to the redemption date on a semi-annual basis
      (assuming a 360-day year consisting of twelve 30-day months) at the Treasury
      Rate (as defined below) plus 15 basis points, plus, in each case, accrued
      interest thereon to the date of redemption.

    

    “Comparable
      Treasury Issue” means the United States Treasury security selected by an
      Independent Investment Banker as having a maturity comparable to the remaining
      term of the Securities that would be utilized, at the time of selection and
      in
      accordance with customary financial practice, in pricing new issues of corporate
      debt securities of comparable maturity to the remaining term of the
      Securities.

    

    “Comparable
      Treasury Price” means, with respect to any redemption date, (1) the average of
      the Reference Treasury Dealer Quotations for such redemption date after
      excluding the highest and lowest such Reference Treasury Dealer Quotations,
      or
      (2) if fewer than four such Reference Treasury Dealer Quotations are obtained,
      the average of all such quotations.

    

    “Independent
      Investment Banker” means one of the Reference Treasury Dealers appointed by the
      Company and reasonably acceptable to the Trustee.

    

    “Reference
      Treasury Dealer” means a primary U. S. government securities dealer in New York
      City selected by the Company and reasonably acceptable to the
      Trustee.

    

    “Reference
      Treasury Dealer Quotations” mean, with respect to each Reference Treasury Dealer
      and any redemption date, the average, as determined by the Trustee, of the
      bid
      and asked prices for the Comparable Treasury Issue (expressed in each case
      as a
      percentage of its principal amount) quoted in writing to the Trustee by such
      Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the
      third Business Day preceding such redemption date.

    

    “Treasury
      Rate” means, with respect to any redemption date, the rate per annum equal to
      the semi-annual equivalent yield to maturity of the Comparable Treasury Issue,
      assuming a price for the Comparable Treasury Issue (expressed as a percentage
      of
      its principal amount) equal to the Comparable Treasury Price for such redemption
      date.

    

    If
      notice
      has been given as provided in the Indenture and funds for redemption of any
      Securities (or any portion thereof) called for redemption shall have been made
      available on the Redemption Date referred to in such notice, such Securities
      (or
      any portion thereof) will cease to bear interest on the date fixed for such
      redemption specified in such notice and the only right of the Holders of such
      Securities will be to receive payment of the Redemption Price.

    

    In
      the
      event of redemption of this Security in part only, a new Security or Securities
      of this Series and of like tenor for the unredeemed portion hereof will be
      issued in the name of the Holder hereof upon the cancellation
      hereof.

    

    The
      Securities of this series will not be subject to any sinking fund.

    

    If
      an
      Event of Default with respect to Securities of this series shall occur and
      be
      continuing, the principal of the Securities of this series may be declared
      due
      and payable in the manner and with the effect provided in the
      Indenture.

    

    Interest
      payments with respect to this Security will be computed and paid on the basis
      of
      a 360-day year of twelve 30-day months for the actual number of days
      elapsed.

    

    The
      Indenture permits, with certain exceptions as therein provided, the amendment
      thereof and the modification of the rights and obligations of the Company and
      the rights of the Holders of the Securities of each series to be affected under
      the Indenture at any time by the Company and the Trustee with the consent of
      the
      Holders of a majority in principal amount of the Securities at the time
      Outstanding of all series to be affected (voting as a class). The Indenture
      also
      contains provisions permitting the Holders of specified percentages in principal
      amount of the Securities of each Series at the time Outstanding, on behalf
      of
      the Holders of all Securities of such series, to waive compliance by the Company
      with certain provisions of the Indenture and certain past defaults under the
      Indenture and their consequences. Any such consent or waiver by the Holder
      of
      this Security shall be conclusive and binding upon such Holder and upon all
      future Holders of this Security and of any Security issued upon the registration
      of transfer hereof or in exchange herefor or in lieu hereof, whether or not
      notation of such consent or waiver is made upon this Security.

    

    No
      reference herein to the Indenture and no provision of this Security or of the
      Indenture shall alter or impair the obligation of the Company, which is absolute
      and unconditional, to pay the principal of, premium, if any, and interest on
      this Security at the times, place and rate, and in the coin or currency, herein
      prescribed.

    

    This
      Security shall be exchangeable for Securities registered in the names of Persons
      other than the Depositary with respect to such series or its nominee only as
      provided in the Indenture. This Security shall be so exchangeable if (x) the
      Depositary notifies the Company that it is unwilling or unable to continue
      as
      Depositary for such series or at any time ceases to be a clearing agency
      registered as such under the Exchange Act, (y) the Company executes and delivers
      to the Trustee an Officers’ Certificate providing that this Security shall be so
      exchangeable or (z) there shall have occurred and be continuing an Event of
      Default with respect to the Securities of such series. Securities so issued
      in
      exchange for this Security shall be of the same series, having the same interest
      rate, if any, and maturity and having the same terms as this Security, in
      authorized denominations and in the aggregate having the same principal amount
      as this Security and registered in such names as the Depositary for such Global
      Security shall direct.

    

    As
      provided in the Indenture and subject to certain limitations therein set forth,
      the transfer of a Security of the series of which this Security is a part is
      registrable in the Security Register, upon surrender of this Security for
      registration of transfer at the office or agency of the Company in any place
      where the principal of and any premium and interest on this Security are
      payable, duly endorsed by, or accompanied by a written instrument of transfer
      in
      form satisfactory to the Company and the Security Registrar duly executed by,
      the Holder hereof or his attorney duly authorized in writing, and thereupon
      one
      or more new Securities of this Series and of like tenor, of authorized
      denominations and for the same aggregate principal amount, will be issued to
      the
      designated transferee or transferees.

    

    The
      Securities of this Series are issuable only in registered form without coupons
      in denominations of $1,000 and any integral multiple thereof. As provided in
      the
      Indenture and subject to certain limitations therein set forth, Securities
      of
      this Series are exchangeable for a like aggregate principal amount of Securities
      of this Series and of like tenor of a different authorized denomination, as
      requested by the Holder surrendering the same.

    

    No
      service charge shall be made for any such registration of transfer or exchange,
      but the Company may require payment of a sum sufficient to cover any tax or
      other governmental charge payable in connection therewith.

    

    Prior
      to
      due presentment of this Security for registration of transfer, the Company,
      the
      Trustee and any agent of the Company or the Trustee may treat the Person in
      whose name this Security is registered as the owner hereof for all purposes,
      whether or not this Security be overdue, and neither the Company, the Trustee
      nor any such agent shall be affected by notice to the contrary.

    

    For
      so
      long as this Security is issued in the form of a Global Security, any notice
      to
      be given to the Holder of this Security shall be deemed to have been duly given
      to such Holder when given to the Depositary, or its nominee, in accordance
      with
      its Applicable Procedures. Neither the Company nor the Trustee will have any
      responsibility with respect to those policies and procedures or for any notices
      or other communications among the Depositary, its direct and indirect
      participants and the beneficial owners of this Security in global
      form.

    

    If
      at any
      time this Security is not represented by a Global Security, any notice to be
      given to the Holder of this Security shall be deemed to have been duly given
      to
      such Holder upon the mailing of such notice to the Holder at such Holder’s
      address as it appears on the Security Register maintained by the Company or
      its
      agent as of the close of business preceding the day such notice is
      given.

    

    Neither
      the failure to give any notice nor any defect in any notice given to the Holder
      of this Security or any other Security of this series will affect the
      sufficiency of any notice given to another Holder of any Securities of this
      series.

    

    Prior
      to
      due presentment of this Security for registration of transfer, the Company,
      the
      Trustee and any agent of the Company or the Trustee may treat the Person in
      whose name this Security is registered as the owner hereof for all purposes,
      whether or not this Security be overdue, and neither the Company, the Trustee
      nor any such agent shall be affected by notice to the contrary.

    

    The
      Indenture provides that the Company, at its option, (a) will be discharged
      from
      any and all obligations in respect of the Securities (except for certain
      obligations to register the transfer or exchange of Securities, replace stolen,
      lost or mutilated Securities, maintain paying agencies and hold moneys for
      payment in trust) or (b) need not comply with certain restrictive covenants
      of
      the Indenture, in each case if the Company deposits, in trust, with the Trustee
      money or U.S. Government Obligations which, through the payment of interest
      thereon and principal thereof in accordance with their terms, will provide
      money, in an amount sufficient to pay all the principal of, and premium, if
      any,
      and interest, if any, on the Securities on the dates such payments are due
      in
      accordance with the terms of such Securities, and certain other conditions
      are
      satisfied.

    

    No
      recourse shall be had for the payment of the principal of or the interest on
      this Security, or for any claim based hereon, or otherwise in respect hereof,
      or
      based on or in respect of the Indenture or any indenture supplemental thereto,
      against any incorporator, organizer, member, limited partner, stockholder,
      officer or director, as such, past, present or future, of the Company or any
      successor Person, whether by virtue of any constitution, statute or rule of
      law,
      or by the enforcement of any assessment or penalty or otherwise, all such
      liability being, by the acceptance hereof and as part of the consideration
      for
      the issuance hereof, expressly waived and released.

    

    This
      Security shall be governed by and construed in accordance with the laws of
      the
      State of New York without regard to principles of conflict of law except Section
      5-1401 of the New York General Obligations Law.

    

    All
      terms
      used in this Security which are defined in the Indenture shall have the meanings
      ascribed to them in the Indenture. 

    

    Unless
      the certificate of authentication hereon has been executed by the Trustee
      referred to herein by manual signature, this Security shall not be entitled
      to
      any benefit under the Indenture or be valid or obligatory for any purpose.
      

    

    IN
      WITNESS WHEREOF, Public Service Company of Oklahoma has caused this instrument
      to be duly executed.

    

    
      	 	
              PUBLIC
                SERVICE COMPANY OF OKLAHOMA

            
	 	 	 
	 	
              By:

            	 
	 	 	
              Assistant
                Treasurer

            

    

    

    This
      is
      one of the Securities of the series designated herein and referred to in the
      within-mentioned Indenture.

    

    
      	
              Date: 
                May 20, 2005

            	 	
              THE
                BANK OF NEW YORK,

            
	 	 	 
	 	
              By:

            	 
	 	 	
              Authorized
                Signatory

            

    

    

    
      
        

      

    FOR
      VALUE
      RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s)
      unto

    

    (PLEASE
      INSERT SOCIAL SECURITY OR OTHER

    IDENTIFYING
      NUMBER OF ASSIGNEE)

    

    _______________________________________

    

    ________________________________________________________________

    

    ________________________________________________________________

    (PLEASE
      PRINT OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF

    ________________________________________________________________

    ASSIGNEE)
      the within Note and all rights thereunder, hereby

    ________________________________________________________________

    irrevocably
      constituting and appointing such person attorney to 

    ________________________________________________________________

    transfer
      such Note on the books of the Issuer, with full

    ________________________________________________________________

    power
      of
      substitution in the premises.

     

    

    Dated:________________________  _________________________

     

    

    NOTICE: The
      signature to this assignment must correspond with the name as written upon
      the
      face of the within Note in every particular, without alteration or enlargement
      or any change whatever and NOTICE: Signature(s) must be guaranteed by a
      financial institution that is a member of the Securities Transfer Agents
      Medallion Program (“STAMP”), the Stock Exchange Medallion Program (“SEMP”) or
      the New York Stock Exchange, Inc. Medallion Signature Program
      (“MSP”).PSO Proposed Form of Sixth Supplemental Indenture

    
      

    

    EXHIBIT 4(d)

     

    

    

    PUBLIC
      SERVICE COMPANY OF OKLAHOMA

     

    and

    

    THE
      BANK
      OF NEW YORK,

    AS
      TRUSTEE

     

    ___________________

    

    

    ________
      SUPPLEMENTAL INDENTURE

    

    Dated
      as
      of ____________, ____

    

    

    Supplemental
      to the Indenture

    dated
      as
      of November 1, 2000

    

    

    ____%
      Senior Notes, Series _, due ____

    

    

    
      
        

      

    

    

    ________
      SUPPLEMENTAL INDENTURE, dated as of ____________, ____, between PUBLIC SERVICE
      COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws
      of
      the State of Oklahoma (the "Company"), and THE BANK OF NEW YORK, a New York
      banking corporation organized and existing under the laws of the State of New
      York, as Trustee under the Original Indenture referred to below (the "Trustee").
      

    

    RECITALS
      OF THE COMPANY

    

    The
      Company has heretofore executed and delivered to the Trustee an indenture dated
      as of November 1, 2000 (the "Original Indenture"), to provide for the issuance
      from time to time of its debentures, notes or other evidences of indebtedness
      (the "Senior Notes"), the form and terms of which are to be established as
      set
      forth in Section 201 and 301 of the Original Indenture.

    

    Section
      901 of the Original Indenture provides, among other things, that the Company
      and
      the Trustee may enter into indentures supplemental to the Original Indenture
      for, among other things, the purpose of establishing the form and terms of
      the
      Senior Notes of any series as permitted in Sections 201 and 301 of the Original
      Indenture.

    

    The
      Company desires to create a series of the Senior Notes in an aggregate principal
      amount of $____________ to be designated the "____% Senior Notes, Series _,
      due
      ____" (the "____% Senior Notes"), and all action on the part of the Company
      necessary to authorize the issuance of the ____% Senior Notes under the Original
      Indenture and this ________ Supplemental Indenture has been duly
      taken.

    

    All
      acts
      and things necessary to make the ____% Senior Notes, when executed by the
      Company and completed, authenticated and delivered by the Trustee as provided
      in
      the Original Indenture and this ________ Supplemental Indenture, the valid
      and
      binding obligations of the Company and to constitute these presents a valid
      and
      binding supplemental indenture and agreement according to its terms, have been
      done and performed.

    

    NOW,
      THEREFORE, THIS ________ SUPPLEMENTAL INDENTURE WITNESSETH:

    

    That
      in
      consideration of the premises and of the acceptance and purchase of the ____%
      Senior Notes by the Holders thereof and of the acceptance of this trust by
      the
      Trustee, the Company covenants and agrees with the Trustee, for the equal
      benefit of the Holders of the ____% Senior Notes, as follows: 

    

    ARTICLE
      ONE

    Definitions

    

    The
      use
      of the terms and expressions herein is in accordance with the definitions,
      uses
      and constructions contained in the Original Indenture and the form of the Global
      Security attached hereto as Exhibit
      A.

    

    ARTICLE
      TWO

    Terms
      and
      Issuance of the ____% Senior Notes

    

    SECTION
      201.     Issue
      of ____% Senior Notes

    

    A
      series
      of Senior Notes which shall be designated the "____% Senior Notes, Series _,
      due
      ____" shall be executed, authenticated and delivered from time to time in
      accordance with the provisions of, and shall in all respects be subject to,
      the
      terms, conditions and covenants of, the Original Indenture and this ________
      Supplemental Indenture (including the form of Global Security set forth in
      Exhibit
      A
      hereto).
      The aggregate principal amount of the ____% Senior Notes, which may be
      authenticated and delivered under this ________ Supplemental Indenture shall
      not, except as permitted by the provisions of the Original Indenture, exceed
      $_____________. 

    

    SECTION
      202.     Form
      of ____% Senior Notes, Incorporation of Terms

    

    The
      ____%
      Senior Notes shall be substantially in the form of the Global Security attached
      hereto as Exhibit
      A.
      The
      terms of such ____% Senior Notes are herein incorporated by reference and are
      part of this ________ Supplemental Indenture.

    

    SECTION
      203.     Depositary
      for Global Securities

    

    The
      Depositary for any Global Securities of the series of which this ____% Senior
      Note is a part shall be The Depository Trust Company in The City of New
      York.

    

    SECTION
      204.     Restrictions
      on Liens

    

    The
      covenant contained in Section 1007 of the Original Indenture shall not be
      applicable to the ____% Senior Notes.

    

    So
      long
      as any of the ____% Senior Notes are outstanding, the Company will not create
      or
      suffer to be created or to exist any additional mortgage, pledge, security
      interest, or other lien (collectively "Liens") on any of its utility properties
      or tangible assets now owned or hereafter acquired to secure any indebtedness
      for borrowed money ("Secured Debt"), without providing that the ____% Senior
      Notes will be similarly secured. This restriction does not apply to the
      Company's subsidiaries, nor will it prevent any of them from creating or
      permitting to exist Liens on their property or assets to secure any Secured
      Debt. Further, this restriction on Secured Debt does not apply to the Company's
      existing first mortgage bonds that have previously been issued under its
      Mortgage and Deed of Trust, dated July 1, 1945, between the Company and Liberty
      Bank and Trust Company of Tulsa, National Association, as successor to The
      first
      National Bank and Trust Company of Tulsa, as Trustee or any indenture
      supplemental thereto; provided that this restriction will apply to future
      issuances thereunder (other than issuances of refunding first mortgage bonds).
      In addition, this restriction does not prevent the creation or existence
      of:

    

    (a) Liens
      on
      property existing at the time of acquisition or construction of such property
      (or created within one year after completion of such acquisition or
      construction), whether by purchase, merger, construction or otherwise, or to
      secure the payment of all or any part of the purchase price or construction
      cost
      thereof, including the extension of any Liens to repairs, renewals,
      replacements, substitutions, betterments, additions, extensions and improvements
      then or thereafter made on the property subject thereto; 

    

    (b) Financing
      of the Company's accounts receivable for electric service; 

    

    (c) Any
      extensions, renewals or replacements (or successive extensions, renewals or
      replacements), in whole or in part, of liens permitted by the foregoing clauses;
      and

    

    (d) The
      pledge of any bonds or other securities at any time issued under any of the
      Secured Debt permitted by the above clauses.

    

    In
      addition to the permitted issuances above, Secured Debt not otherwise so
      permitted may be issued in an amount that does not exceed 15% of Net Tangible
      Assets as defined below. 

    

    "Net
      Tangible Assets" means the total of all assets (including revaluations thereof
      as a result of commercial appraisals, price level restatement or otherwise)
      appearing on the Company's balance sheet, net of applicable reserves and
      deductions, but excluding goodwill, trade names, trademarks, patents,
      unamortized debt discount and all other like intangible assets (which term
      shall
      not be construed to include such revaluations), less the aggregate of the
      Company's current liabilities appearing on such balance sheet. For purposes
      of
      this definition, the Company's balance sheet does not include assets and
      liabilities of its subsidiaries.

    

    This
      restriction also does not apply to or prevent the creation or existence of
      leases made, or existing on property acquired, in the ordinary course of
      business.

    

    SECTION
      205.     Place
      of Payment

    

    The
      Place
      of Payment in respect of the ____% Senior Notes will be at the principal office
      or place of business of the Trustee or its successor in trust under the
      Indenture, which, at the date hereof, is located at 101 Barclay Street, New
      York, NY 10281, Attention: Corporate Trust Trustee.

    

    SECTION
      206.      Sinking
      Funds.

    

    Article
      Twelve of the Indenture shall not apply to the Series _ Notes.

    

    SECTION
      207.     Redemption

    

    The
      ____%
      Senior Notes shall be redeemable at the option of the Company, in whole at
      any
      time or in part from time to time, upon not less than thirty but not more than
      sixty days' previous notice given by mail to the registered owners of the ____%
      Senior Notes at a redemption price equal to the greater of (i) 100% of the
      principal amount of the ____% Senior Notes being redeemed and (ii) the sum
      of
      the present values of the remaining scheduled payments of principal and interest
      on the ____% Senior Notes being redeemed (excluding the portion of any such
      interest accrued to the date of redemption) discounted (for purposes of
      determining present value) to the redemption date on a semi-annual basis
      (assuming a 360-day year consisting of twelve 30-day months) at the Treasury
      Rate (as defined below) plus 20 basis points, plus, in each case, accrued
      interest thereon to the date of redemption.

    

    "Comparable
      Treasury Issue" means the United States Treasury security selected by an
      Independent Investment Banker as having a maturity comparable to the remaining
      term of the ____%
      Senior Notes
      that would be utilized, at the time of selection and in accordance with
      customary financial practice, in pricing new issues of corporate debt securities
      of comparable maturity to the remaining term of the Notes.

    

    "Comparable
      Treasury Price" means, with respect to any redemption date, (i) the average
      of
      the bid and asked prices for the Comparable Treasury Issue (expressed in each
      case a percentage of its principal amount) on the third Business Day preceding
      such redemption date, as set forth in the daily statistical release (or any
      successor release) published by the Federal Reserve Bank of New York and
      designated "Composite 3:30 p.m. Quotations for U. S. Government Securities"
      or
      (ii) if such release (or any successor release) is not published or does not
      contain such prices on such third Business Day, the Reference Treasury Dealer
      Quotation for such redemption date.

    

    "Independent
      Investment Banker" means one of the Reference Treasury Dealers appointed by
      the
      Company and reasonably acceptable to the Trustee.

    

    "Reference
      Treasury Dealer" means a primary U.S. government securities dealer in New York
      City selected by the Company and reasonably acceptable to the
      Trustee.

    

    "Reference
      Treasury Dealer Quotation" means, with respect to the Reference Treasury Dealer
      and any redemption date, the average, as determined by the Trustee, of the
      bid
      and asked prices for the Comparable Treasury Issue (expressed in each case
      as a
      percentage of its principal amount) quoted in writing to the Trustee by such
      Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the
      third Business Day preceding such redemption date.

    

    "Treasury
      Rate" means, with respect to any redemption date, the rate per annum equal
      to
      the semi-annual equivalent yield to maturity of the Comparable Treasury Issue,
      assuming a price for the Comparable Treasury Issue (expressed as a percentage
      of
      its principal amount) equal to the Comparable Treasury Price for such redemption
      date.

    ARTICLE
      THREE

    Miscellaneous

    

    SECTION
      301.     Execution
      as Supplemental Indenture

    

    This
      ________ Supplemental Indenture is executed and shall be construed as an
      indenture supplemental to the Original Indenture and, as provided in the
      Original Indenture, this ________ Supplemental Indenture forms a part
      thereof.

    

    SECTION
      302.     Conflict
      with Trust Indenture Act

    

    If
      any
      provision hereof limits, qualifies or conflicts with another provision hereof
      which is required to be included in this ________ Supplemental Indenture by
      any
      of the provisions of the Trust Indenture Act, such required provision shall
      control. 

    

    SECTION
      303.     Effect
      of Headings

    

    The
      Article and Section headings herein are for convenience only and shall not
      affect the construction hereof.

    

    SECTION
      304.     Successors
      and Assigns

    

    All
      covenants and agreements by the Company in this ________ Supplemental Indenture
      shall bind its successors and assigns, whether so expressed or not.

    

    SECTION
      305.     Separability
      Clause

    

    In
      case
      any provision in this ________ Supplemental Indenture or in the ____% Senior
      Notes shall be invalid, illegal or unenforceable, the validity, legality and
      enforceability of the remaining provisions shall not in any way be affected
      or
      impaired thereby.

    

    SECTION
      306.     Benefits
      of ________ Supplemental Indenture

    

    Nothing
      in this ________ Supplemental Indenture or in the ____% Senior Notes, express
      or
      implied, shall give to any Person, other than the parties hereto and their
      successors hereunder and the Holders, any benefit or any legal or equitable
      right, remedy or claim under this ________ Supplemental Indenture.

    

    SECTION
      307.    Execution
      and Counterparts

    

    This
      ________ Supplemental Indenture may be executed in any number of counterparts,
      each of which shall be deemed to be an original, but all such counterparts
      shall
      together constitute but one and the same instrument.

    IN
      WITNESS WHEREOF, the parties hereto have caused this ________ Supplemental
      Indenture to be duly executed and their respective corporate seals to be
      hereunto affixed and attested, all as of the day and year first above written.
      

    

    
      	 	
              PUBLIC
                SERVICE COMPANY OF OKLAHOMA

            
	 	 	 
	 	
              By:

            	
              /s/   

            
	 	 	
              Assistant
                Treasurer

            
	
              Attest:

            	 	 
	
              /s/
                    

            	 	 
	
              Assistant
                Secretary

            	 	 
	 	 	 
	 	 	
              THE
                BANK OF NEW YORK,

            
	 	 	
              as
                Trustee

            
	 	 	 
	 	
              By:

            	
              /s/  

            
	 	 	
              Authorized
                Signatory

            
	
              Attest:

            	 	 
	
              /s/   

            	 	 
	
              Name: 

            	 	 
	
              Title: 

            	 	 

    

    

    

    
      	
              STATE
                OF OHIO

            	
              )

            	 
	 	
              )

            	
              ss:

            
	
              COUNTY
                OF FRANKLIN

            	
              )

            	 

    

    

    On
      the
      ____ day of __________, ____, before me personally came _______________, to
      me
      known, who, being by me duly sworn, did depose and say that ___ is an Assistant
      Treasurer of Public Service Company of Oklahoma, one of the corporations
      described in and which executed the foregoing instrument; that ____knows the
      seal of said corporation; that the seal affixed to said instrument is such
      corporate seal; that it was so affixed by authority of the Board of Directors
      of
      said corporation, and that ___ signed ___ name thereto by like authority.

    

    
      	 	
               

            
	 	
              My
                Commission expires 

            

    

    

    

    
      	
              STATE
                OF NEW YORK

            	
              )

            	 
	 	
              )

            	
              ss:

            
	
              COUNTY
                OF NEW YORK

            	
              )

            	 

    

     

    On
      the
      ____ day of __________, ____, before me personally came _______________, to
      me
      known, who, being by me duly sworn, did depose and say that ___ is an Assistant
      Treasurer of The Bank of New York, a New York banking corporation, one of the
      corporations described in and which executed the foregoing instrument; that
      ___
      knows the seal of said corporation; that the seal affixed to said instrument
      is
      such corporate seal; that it was so affixed by authority of the Board of
      Directors of said corporation, and that ___ signed ___ name thereto by like
      authority. 

    

    

    
      	 	
               

            
	 	
              My
                Commission expires 

            

    

     

    

    
      

    

    EXHIBIT
      A
      to EXHIBIT 4(d)

    

    [Form
      of
      Face of Global Security]

    

    THIS
      SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER
      REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE OF A
      DEPOSITARY. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE
      NAME
      OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED
      CIRCUMSTANCES DESCRIBED IN THE INDENTURE, AND NO TRANSFER OF THIS SECURITY
      (OTHER THAN A TRANSFER OF THIS SECURITY AS A WHOLE BY THE DEPOSITARY TO A
      NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY
      OR
      ANOTHER NOMINEE OF THE DEPOSITARY) MAY BE REGISTERED EXCEPT IN LIMITED
      CIRCUMSTANCES. 

    

    Unless
      this certificate is presented by an authorized representative of The Depository
      Trust Company, a New York corporation ("DTC"), to Public Service Company of
      Oklahoma or its agent for registration of transfer, exchange or payment, and
      any
      definitive certificate issued is registered in the name of Cede & Co. or in
      such other name as is requested by an authorized representative of DTC (and
      any
      payment is made to Cede & Co. or to such other entity as is requested by an
      authorized representative of DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF
      FOR
      VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL in as much as the registered
      owner hereof, Cede & Co., has an interest herein.

    

    No.
      R-1

    PUBLIC
      SERVICE COMPANY OF OKLAHOMA

    ____%
      Senior Notes, Series _, due ____

    

     

    
      
        	
                CUSIP
                  No. __________

              	
                $____________

              

      

    

    PUBLIC
      SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under
      the
      laws of the State of Oklahoma (the "Company", which term includes any successor
      Person under the Indenture hereinafter referred to), for value received, hereby
      promises to pay to CEDE & CO. or registered assigns, the principal sum of
      _________________________
      DOLLARS
      ($____________) on ____________, ____ (the "Final Maturity"), and to pay
      interest thereon from ____________, ____ or from the most recent Interest
      Payment Date to which interest has been paid or duly provided for, semi-annually
      on March 15 and ____________ each year, commencing March 15, ____, at the
      interest rate per annum specified above, until the principal amount shall have
      been paid or duly provided for. Interest shall be computed on the basis of
      a
      360-day year of twelve 30-day months.

    

    The
      interest so payable, and punctually paid or duly provided for, on any Interest
      Payment Date will, as provided in such Indenture, be paid to the Person in
      whose
      name this Security (or one or more Predecessor Securities) is registered at
      the
      close of business on the Regular Record Date for such interest, which shall
      be
      the February 28 or August 31 (whether or not a Business Day) immediately
      preceding the Interest Payment Date. Any such interest not so punctually paid
      or
      duly provided for will forthwith cease to be payable to the Holder on such
      Regular Record Date and may either be paid to the Person in whose name this
      Security (or one or more Predecessor Securities) is registered at the close
      of
      business on a Special Record Date for the payment of such Defaulted Interest
      to
      be fixed by the Trustee, notice whereof shall be given to Holders of Securities
      of this series not less than 10 days prior to such Special Record Date, or
      be
      paid at any time in any other lawful manner not inconsistent with the
      requirements of any securities exchange on which the Securities of this series
      may be listed, and upon such notice as may be required by such exchange, all
      as
      more fully provided in said Indenture.

    

    Payment
      of the principal of (and premium, if any) and interest on this Security will
      be
      made at the office or agency of the Company maintained for that purpose in
      the
      Borough of Manhattan, The City of New York, New York, in such coin or currency
      of the United States of America as at the time of payment is legal tender for
      the payment of public and private debts; provided, however, that at the option
      of the Company payment of interest may be made by check mailed to the address
      of
      the Person entitled thereto as such address shall appear in the Security
      Register.

    

    This
      Security has initially been issued in the form of a Global Security, and the
      Company has initially designated The Depository Trust Company (the "Depositary",
      which term shall include any successor depositary) as the depositary for this
      Security. For as long as this Security or any portion hereof is issued in such
      form, and notwithstanding the previous paragraph, all payments of interest,
      principal and other amounts in respect of this Security or portion thereof
      shall
      be made to the Depositary or its nominee in accordance with the Applicable
      Procedures in the coin or currency specified above and as further provided
      herein.

    

    This
      Security is one of a duly authorized issue of securities of the Company (the
      "Securities"), issued and to be issued in one or more series under an Indenture,
      dated as of November 1, 2000, as amended and supplemented from time to time
      (the
      "Indenture", which term shall have the meaning assigned to it in such
      instrument), between the Company and The Bank of New York, a New York banking
      corporation, as Trustee (the "Trustee", which term includes any successor
      trustee under the Indenture), as to which Indenture and all indentures
      supplemental thereto reference is hereby made for a statement of the respective
      rights, limitations of rights, duties and immunities thereunder of the Company,
      the Trustee and the Holders and of the terms upon which the Securities are,
      and
      are to be, authenticated and delivered. This Security is one of the series
      designated on the face hereof, limited in aggregate principal amount to
      $____________; provided, however, the aggregate principal amount hereof can
      be
      increased, without the consent of the Holder, as permitted by the provisions
      of
      the Original Indenture. The provisions of this Security, together with the
      provisions of the Indenture, shall govern the rights, obligations, duties and
      immunities of the Holder, the Company and the Trustee with respect to this
      Security, provided that, if any provision of this Security necessarily conflicts
      with any provision of the Indenture, the provision of this Security shall be
      controlling to the fullest extent permitted under the Indenture.

    

    The
      Securities of this Series are subject to redemption upon not less than 30 nor
      more than 60 days' notice by mail to the Holders of such Securities at their
      addresses in the Security Register for such Series at the option of the Company,
      in whole or in part, from time to time at a Redemption Price equal to
the
      greater of (i) 100% of the principal amount of the Notes being redeemed and
      (ii)
      the sum of the present values of the remaining scheduled payments of principal
      and interest on the Notes being redeemed (excluding the portion of any such
      interest accrued to the date of redemption) discounted (for purposes of
      determining present value) to the redemption date on a semi-annual basis
      (assuming a 360-day year consisting of twelve 30-day months) at the Treasury
      Rate (as defined below) plus 20 basis points, plus, in each case, accrued
      interest thereon to the date of redemption.

    

    "Comparable
      Treasury Issue" means the United States Treasury security selected by an
      Independent Investment Banker as having a maturity comparable to the remaining
      term of the Notes that would be utilized, at the time of selection and in
      accordance with customary financial practice, in pricing new issues of corporate
      debt securities of comparable maturity to the remaining term of the
      Notes.

    

    "Comparable
      Treasury Price" means, with respect to any redemption date, (1) the average
      of
      the bid and asked prices for the Comparable Treasury Issue (expressed in each
      case as a percentage of its principal amount) on the third Business Day
      preceding such redemption date, as set forth in the daily statistical release
      (or any successor release) published by the Federal Reserve Bank of New York
      and
      designated "Composite 3:30 p.m. Quotations for U.S. Government Securities"
      or
      (2) if such release (or any successor release) is not published or does not
      contain such prices on such third Business Day, the Reference Treasury Dealer
      Quotation for such redemption date.

    

    "Independent
      Investment Banker" means one of the Reference Treasury Dealers appointed by
      the
      Company and reasonably acceptable to the Trustee.

    

    "Reference
      Treasury Dealer" means a primary U. S. government securities dealer in New
      York
      City selected by the Company and reasonably acceptable to the
      Trustee.

    

    "Reference
      Treasury Dealer Quotation" means, with respect to the Reference Treasury Dealer
      and any redemption date, the average, as determined by the Trustee, of the
      bid
      and asked prices for the Comparable Treasury Issue (expressed in each case
      as a
      percentage of its principal amount) quoted in writing to the Trustee by such
      Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the
      third Business Day preceding such redemption date.

    

    "Treasury
      Rate" means, with respect to any redemption date, the rate per annum equal
      to
      the semi-annual equivalent yield to maturity of the Comparable Treasury Issue,
      assuming a price for the Comparable Treasury Issue (expressed as a percentage
      of
      its principal amount) equal to the Comparable Treasury Price for such redemption
      date.

    

    If
      notice
      has been given as provided in the Indenture and funds for redemption of any
      Securities (or any portion thereof) called for redemption shall have been made
      available on the Redemption Date referred to in such notice, such Securities
      (or
      any portion thereof) will cease to bear interest on the date fixed for such
      redemption specified in such notice and the only right of the Holders of such
      Securities will be to receive payment of the Redemption Price.

    

    In
      the
      event of redemption of this Security in part only, a new Security or Securities
      of this Series and of like tenor for the unredeemed portion hereof will be
      issued in the name of the Holder hereof upon the cancellation
      hereof.

    

    The
      Securities of this series will not be subject to any sinking fund.

    

    If
      an
      Event of Default with respect to Securities of this series shall occur and
      be
      continuing, the principal of the Securities of this series may be declared
      due
      and payable in the manner and with the effect provided in the
      Indenture.

    

    Interest
      payments with respect to this Security will be computed and paid on the basis
      of
      a 360-day year of twelve 30-day months for the actual number of days
      elapsed.

    

    The
      Indenture permits, with certain exceptions as therein provided, the amendment
      thereof and the modification of the rights and obligations of the Company and
      the rights of the Holders of the Securities of each series to be affected under
      the Indenture at any time by the Company and the Trustee with the consent of
      the
      Holders of a majority in principal amount of the Securities at the time
      Outstanding of all series to be affected (voting as a class). The Indenture
      also
      contains provisions permitting the Holders of specified percentages in principal
      amount of the Securities of each Series at the time Outstanding, on behalf
      of
      the Holders of all Securities of such series, to waive compliance by the Company
      with certain provisions of the Indenture and certain past defaults under the
      Indenture and their consequences. Any such consent or waiver by the Holder
      of
      this Security shall be conclusive and binding upon such Holder and upon all
      future Holders of this Security and of any Security issued upon the registration
      of transfer hereof or in exchange herefor or in lieu hereof, whether or not
      notation of such consent or waiver is made upon this Security.

    

    No
      reference herein to the Indenture and no provision of this Security or of the
      Indenture shall alter or impair the obligation of the Company, which is absolute
      and unconditional, to pay the principal of, premium, if any, and interest on
      this Security at the times, place and rate, and in the coin or currency, herein
      prescribed.

    

    This
      Security shall be exchangeable for Securities registered in the names of Persons
      other than the Depositary with respect to such series or its nominee only as
      provided in the Indenture. This Security shall be so exchangeable if (x) the
      Depositary notifies the Company that it is unwilling or unable to continue
      as
      Depositary for such series or at any time ceases to be a clearing agency
      registered as such under the Exchange Act, (y) the Company executes and delivers
      to the Trustee an Officers' Certificate providing that this Security shall
      be so
      exchangeable or (z) there shall have occurred and be continuing an Event of
      Default with respect to the Securities of such series. Securities so issued
      in
      exchange for this Security shall be of the same series, having the same interest
      rate, if any, and maturity and having the same terms as this Security, in
      authorized denominations and in the aggregate having the same principal amount
      as this Security and registered in such names as the Depositary for such Global
      Security shall direct.

    

    As
      provided in the Indenture and subject to certain limitations therein set forth,
      the transfer of a Security of the series of which this Security is a part is
      registrable in the Security Register, upon surrender of this Security for
      registration of transfer at the office or agency of the Company in any place
      where the principal of and any premium and interest on this Security are
      payable, duly endorsed by, or accompanied by a written instrument of transfer
      in
      form satisfactory to the Company and the Security Registrar duly executed by,
      the Holder hereof or his attorney duly authorized in writing, and thereupon
      one
      or more new Securities of this Series and of like tenor, of authorized
      denominations and for the same aggregate principal amount, will be issued to
      the
      designated transferee or transferees.

    

    The
      Securities of this Series are issuable only in registered form without coupons
      in denominations of $1,000 and any integral multiple thereof. As provided in
      the
      Indenture and subject to certain limitations therein set forth, Securities
      of
      this Series are exchangeable for a like aggregate principal amount of Securities
      of this Series and of like tenor of a different authorized denomination, as
      requested by the Holder surrendering the same.

    

    No
      service charge shall be made for any such registration of transfer or exchange,
      but the Company may require payment of a sum sufficient to cover any tax or
      other governmental charge payable in connection therewith.

    

    Prior
      to
      due presentment of this Security for registration of transfer, the Company,
      the
      Trustee and any agent of the Company or the Trustee may treat the Person in
      whose name this Security is registered as the owner hereof for all purposes,
      whether or not this Security be overdue, and neither the Company, the Trustee
      nor any such agent shall be affected by notice to the contrary.

    

    For
      so
      long as this Security is issued in the form of a Global Security, any notice
      to
      be given to the Holder of this Security shall be deemed to have been duly given
      to such Holder when given to the Depositary, or its nominee, in accordance
      with
      its Applicable Procedures. Neither the Company nor the Trustee will have any
      responsibility with respect to those policies and procedures or for any notices
      or other communications among the Depositary, its direct and indirect
      participants and the beneficial owners of this Security in global
      form.

    

    If
      at any
      time this Security is not represented by a Global Security, any notice to be
      given to the Holder of this Security shall be deemed to have been duly given
      to
      such Holder upon the mailing of such notice to the Holder at such Holder's
      address as it appears on the Security Register maintained by the Company or
      its
      agent as of the close of business preceding the day such notice is
      given.

    

    Neither
      the failure to give any notice nor any defect in any notice given to the Holder
      of this Security or any other Security of this series will affect the
      sufficiency of any notice given to another Holder of any Securities of this
      series.

    

    Prior
      to
      due presentment of this Security for registration of transfer, the Company,
      the
      Trustee and any agent of the Company or the Trustee may treat the Person in
      whose name this Security is registered as the owner hereof for all purposes,
      whether or not this Security be overdue, and neither the Company, the Trustee
      nor any such agent shall be affected by notice to the contrary.

    

    The
      Indenture provides that the Company, at its option, (a) will be discharged
      from
      any and all obligations in respect of the Securities (except for certain
      obligations to register the transfer or exchange of Securities, replace stolen,
      lost or mutilated Securities, maintain paying agencies and hold moneys for
      payment in trust) or (b) need not comply with certain restrictive covenants
      of
      the Indenture, in each case if the Company deposits, in trust, with the Trustee
      money or U.S. Government Obligations which, through the payment of interest
      thereon and principal thereof in accordance with their terms, will provide
      money, in an amount sufficient to pay all the principal of, and premium, if
      any,
      and interest, if any, on the Securities on the dates such payments are due
      in
      accordance with the terms of such Securities, and certain other conditions
      are
      satisfied.

    

    No
      recourse shall be had for the payment of the principal of or the interest on
      this Security, or for any claim based hereon, or otherwise in respect hereof,
      or
      based on or in respect of the Indenture or any indenture supplemental thereto,
      against any incorporator, organizer, member, limited partner, stockholder,
      officer or director, as such, past, present or future, of the Company or any
      successor Person, whether by virtue of any constitution, statute or rule of
      law,
      or by the enforcement of any assessment or penalty or otherwise, all such
      liability being, by the acceptance hereof and as part of the consideration
      for
      the issuance hereof, expressly waived and released.

    

    This
      Security shall be governed by and construed in accordance with the laws of
      the
      State of New York without regard to principles of conflict of law except Section
      5-1401 of the New York General Obligations Law.

    

    All
      terms
      used in this Security which are defined in the Indenture shall have the meanings
      ascribed to them in the Indenture. 

    

    Unless
      the certificate of authentication hereon has been executed by the Trustee
      referred to herein by manual signature, this Security shall not be entitled
      to
      any benefit under the Indenture or be valid or obligatory for any purpose.
      

    

     

    IN
      WITNESS WHEREOF, Public Service Company of Oklahoma has caused this instrument
      to be duly executed under its corporate seal. 

    

    
      	 	
              PUBLIC
                SERVICE COMPANY OF OKLAHOMA

            
	 	 	 
	 	
              By:

            	 
	 	 	
              Assistant
                Treasurer

            

    

    

    

    This
      is
      one of the Securities of the series designated herein and referred to in the
      within-mentioned Indenture.

    

    
      	
              Dated:
                _______________

            	
              THE
                BANK OF NEW YORK

            
	 	 	 
	 	
              By:

            	 
	 	 	
              Authorized
                Signatory

            

    

    

    
      

    

    FOR
      VALUE
      RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s)
      unto

    

    (PLEASE
      INSERT SOCIAL SECURITY OR OTHER

    IDENTIFYING
      NUMBER OF ASSIGNEE)

    

    _______________________________________

    

    ________________________________________________________________

    

    ________________________________________________________________

    (PLEASE
      PRINT OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF

    ________________________________________________________________

    ASSIGNEE)
      the within Note and all rights thereunder, hereby

    ________________________________________________________________

    irrevocably
      constituting and appointing such person attorney to 

    ________________________________________________________________

    transfer
      such Note on the books of the Issuer, with full

    ________________________________________________________________

    power
      of
      substitution in the premises.

    

    

    Dated:________________________  _________________________

    

     

    NOTICE: The
      signature to this assignment must correspond with the name as written upon
      the
      face of the within Note in every particular, without alteration or enlargement
      or any change whatever and NOTICE: Signature(s) must be guaranteed by a
      financial institution that is a member of the Securities Transfer Agents
      Medallion Program ("STAMP"), the Stock Exchange Medallion Program ("SEMP")
      or
      the New York Stock Exchange, Inc. Medallion Signature Program
      ("MSP").

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