<PAGE>
                                                              EXHIBIT 4(b) (3)
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                             PUBLIC SERVICE COMPANY
                                   OF COLORADO


                                       TO


                            FIRST TRUST OF NEW YORK,
                              NATIONAL ASSOCIATION,


                                                                  AS TRUSTEE


                              _____________________ 



                          SUPPLEMENTAL INDENTURE NO. 5

                          Dated as of November 1, 1996


                          Supplemental to the Indenture
                           dated as of October 1, 1993


                              _____________________ 


                   Establishing the Securities of Series No. 4
                 designated Secured Medium-Term Notes, Series B


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<PAGE>
     SUPPLEMENTAL INDENTURE NO. 5, dated as of November 1, 1996, between PUBLIC 
SERVICE COMPANY OF COLORADO, a corporation duly organized and existing under the
laws of the State of Colorado (hereinafter sometimes called the "Company"), and
FIRST TRUST OF NEW YORK, NATIONAL ASSOCIATION, a national banking association
(hereinafter sometimes called the "Trustee"), as successor trustee to Morgan
Guaranty Trust Company of New York under the Indenture, dated as of October 1,
1993 (hereinafter called the "Original Indenture"), as previously supplemented
and as further supplemented by this Supplemental Indenture No. 5.  The Original 
Indenture and any and all indentures and other instruments supplemental thereto
are hereinafter sometimes collectively called the "Indenture".

                             RECITALS OF THE COMPANY

     The Original Indenture was authorized, executed and delivered by the
Company to provide for the issuance from time to time of its Securities (such
term and all other capitalized terms used herein without definition having the
meanings assigned to them in the Original Indenture), to be issued in one or
more series as contemplated therein, and to provide security for the payment of
the principal of and premium, if any, and interest, if any, on the Securities.

     The Company has heretofore executed and delivered to the Trustee the
Supplemental Indentures referred to in Schedule A hereto for the purpose of
establishing various series of bonds and of appointing the successor trustee. 

     The Company desires to establish a series of Securities to be designated
"Secured Medium-Term Notes, Series B", being a series of First Collateral Trust
Bonds, such series of Securities to be hereinafter sometimes called "Series 
No. 4".

     The Company has duly authorized the execution and delivery of this
Supplemental Indenture No. 5 to establish the Securities of Series No. 4 and has
duly authorized the issuance of such Securities; and all acts necessary to make
this Supplemental Indenture No. 5 a valid agreement of the Company, and to make
the Securities of Series No. 4 valid obligations of the Company, have been
performed.

                                GRANTING CLAUSES

     NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE NO. 5 WITNESSETH, that, in
consideration of the premises and of the purchase of the Securities by the
Holders thereof, and in order to secure the payment of the principal of and
premium, if any, and interest, if any, on all Securities from time to time
Outstanding and the performance of the covenants contained therein and in the
Indenture and to declare the terms and conditions on which such Securities are
secured, the Company hereby grants, bargains, sells, releases, conveys, assigns,
transfers, mortgages, pledges, sets over and confirms to the Trustee, and grants
to the Trustee a security interest in, the following:

                              GRANTING CLAUSE FIRST

          All right, title and interest of the Company, as of the date of
     the execution and delivery of this Supplemental Indenture No. 5, in
     and to property (other than Excepted Property), real, personal and
     mixed and wherever situated, in any case used or to be used in or in
     connection with the Electric Utility Business (whether or not such use
     is the sole use of such property), including without limitation (a)
     all lands, easements, servitudes, licenses, permits, rights of way and
     other rights and interests in or relating to real property used or to
     be used in or in connection with the Electric Utility Business or
     relating to the occupancy or use of such real property, subject

<PAGE>

     however, to the exceptions and exclusions set forth in clause (a) of
     Granting Clause First of the Original Indenture; (b) all plants,
     generators, turbines, engines, boilers, fuel handling and
     transportation facilities, air and water pollution control and sewage
     and solid waste disposal facilities and other machinery and facilities
     for the generation of electric energy; (c) all switchyards, lines,
     towers, substations, transformers and other machinery and facilities
     for the transmission of electric energy; (d) all lines, poles,
     conduits, conductors, meters, regulators and other machinery and
     facilities for the distribution of electric energy; (e) all buildings,
     offices, warehouses and other structures used or to be used in or in
     connection with the Electric Utility Business; (f) all pipes, cables,
     insulators, ducts, tools, computers and other data processing and/or
     storage equipment and other equipment, apparatus and facilities used
     or to be used in or in connection with the Electric Utility Business;
     (g) any or all of the foregoing properties in the process of
     construction; and (h) all other property, of whatever kind and nature,
     ancillary to or otherwise used or to be used in conjunction with any
     or all of the foregoing or otherwise, directly or indirectly, in
     furtherance of the Electric Utility Business;

                             GRANTING CLAUSE SECOND

          Subject to the applicable exceptions permitted by Section 810(c),
     Section 1303 and Section 1305 of the Original Indenture, all property
     (other than Excepted Property) of the kind and nature described in
     Granting Clause First which may be hereafter acquired by the Company,
     it being the intention of the Company that all such property acquired
     by the Company after the date of the execution and delivery of this
     Supplemental Indenture No. 5 shall be as fully embraced within and
     subjected to the Lien hereof as if such property were owned by the
     Company as of the date of the execution and delivery of this
     Supplemental Indenture No. 5;

                             GRANTING CLAUSE FOURTH

          All other property of whatever kind and nature subjected or
     required to be subjected to the Lien of the Indenture by any of the
     provisions thereof;

                                EXCEPTED PROPERTY

          Expressly excepting and excluding, however, from the Lien and
     operation of the Indenture all Excepted Property of the Company,
     whether now owned or hereafter acquired;

     TO HAVE AND TO HOLD all such property, real, personal and mixed, unto the
Trustee, its successors in trust and their assigns forever;

     SUBJECT, HOWEVER, to (a) Liens existing at the date of the execution and
delivery of the Original Indenture (including, but not limited to, the Lien of
the PSCO 1939 Mortgage), (b) as to property acquired by the Company after the
date of the execution and delivery of the Original Indenture, Liens existing or
placed thereon at the time of the acquisition thereof (including, but not
limited to, the Lien of any Class A Mortgage and purchase money Liens), (c)
Retained Interests and (d) any other Permitted Liens, it being understood that,
with respect to any property which was at the date of execution and delivery of
the Original Indenture or thereafter became or hereafter becomes 


                                      2

<PAGE>

subject to the Lien of any Class A Mortgage, the Lien of the Indenture shall 
at all times be junior, subject and subordinate to the Lien of such Class A 
Mortgage;

     IN TRUST, NEVERTHELESS, for the equal and proportionate benefit and
security of the Holders from time to time of all Outstanding Securities without
any priority of any such Security over any other such Security;

     PROVIDED, HOWEVER, that the right, title and interest of the Trustee in and
to the Mortgaged Property shall cease, terminate and become void in accordance
with, and subject to the conditions set forth in, Article Nine of the Original
Indenture, and if, thereafter, the principal of and premium, if any, and
interest, if any, on the Securities shall have been paid to the Holders thereof,
or shall have been paid to the Company pursuant to Section 603 of the Original
Indenture, then and in that case the Indenture shall terminate, and the Trustee
shall execute and deliver to the Company such instruments as the Company shall
require to evidence such termination; otherwise the Indenture, and the estate
and rights thereby granted, shall be and remain in full force and effect; and

     THE PARTIES HEREBY FURTHER COVENANT AND AGREE as follows:

                                   ARTICLE ONE

                           SECURITIES OF SERIES NO. 4

     There are hereby established the Securities of Series No. 4, which shall
have the terms and characteristics set forth below (the lettered subdivisions
set forth below corresponding to the lettered subdivisions of Section 301 of the
Original Indenture):

     (a)  the title of the Securities of such series shall be "Secured
     Medium-Term Notes, Series B", being a series of First Collateral Trust
     Bonds; provided, however, that, at any time after the PSCO 1939
     Mortgage shall have been satisfied and discharged, the Company shall
     have the right, without any consent or other action by the Holders of 
     such Securities, to change such title in such manner as shall be
     deemed by the Company to be appropriate to reflect such satisfaction
     and discharge, such change to be evidenced in an Officer's
     Certificate; 

     (b)  there shall be no limit upon the aggregate principal amount of
     the Securities of Series No. 4 which may be authenticated and
     delivered under the Indenture.  The Securities of Series No. 4 shall
     be initially authenticated and delivered from time to time in the
     aggregate principal amount of up to $250,000,000;

     (c)  interest on the Securities of Series No. 4 shall be payable to
     the Persons in whose names such Securities are registered at the close
     of business on the Regular Record Date for such interest, except as
     otherwise expressly provided in the form of such Security attached as
     Exhibit A hereto;

     (d)  the principal of each Security of Series No. 4 shall be payable
     on such date as is specified in the Officer's Certificate applicable
     to such Security;

     (e)  an Officer's Certificate with respect to each Security of Series
     No. 4 shall specify the rate at which such Security of Series No. 4
     shall bear interest, the date from which interest shall accrue, the
     Interest Payment Dates if other than February 1 


                                      3

<PAGE>

     and August 1 of each year and the Regular Record Dates with respect to
     the Interest Payment Dates if other than January 15 and July 15;

     (f)  the Corporate Trust Office of First Trust of New York, National
     Association, in New York, New York shall be the place at which (i) the
     principal of, premium, if any, and interest, if any, on the Securities
     of Series No. 4 shall be payable, (ii) registration of transfer of
     such Securities may be effected, (iii) exchanges of such Securities
     may be effected and (iv) notices and demands to or upon the Company in
     respect of such Securities and the Indenture may be served; and First
     Trust of New York, National Association, shall be the Security
     Registrar for the Securities; provided, however, that the Company
     reserves the right to change, by one or more Officer's Certificates,
     any such place or the Security Registrar; and provided, further, that
     the Company reserves the right to designate, by one or more Officer's
     Certificates, its principal office in Denver, Colorado as any such
     place or itself as the Security Registrar;

     (g)  each Security of Series No. 4 shall be redeemable only if and to
     the extent specified in the Officer's Certificate applicable to such
     Security of Series No. 4;

     (h)  not applicable to any Security of Series No. 4, except to the extent
     specified in the Officer's Certificate applicable to a particular Security
     of Series No. 4;

     (i)  the Securities of Series No. 4 shall be issuable in denominations of
     $100,000 and any greater amount which is an integral multiple of $1,000;

     (j)  not applicable;

     (k)  not applicable;

     (l)  not applicable;

     (m)  not applicable;

     (n)  not applicable to any Security of Series No. 4, except to the extent
     specified in the Officer's Certificate applicable to a particular Security
     of Series No. 4;

     (o)  not applicable;

     (p)  not applicable;

     (q)  each Security of Series No. 4 is to be initially registered in the
     name of Cede & Co., as nominee for The Depository Trust Company (the
     "Depositary").  The Securities of Series No. 4 shall not be transferable or
     exchangeable, nor shall any purported transfer be registered, except as
     follows:

          (i) a Security of Series No. 4 may be transferred in whole, and
          appropriate registration of transfer effected, if such transfer is by
          such nominee to the Depositary, or by the Depositary to another
          nominee thereof, or by any nominee of the Depositary to any other
          nominee thereof, or by the Depositary or any nominee thereof to any
          successor securities depositary or any nominee thereof; and


                                      4

<PAGE>

          (ii) a Security of Series No. 4 may be exchanged for certificated 
          notes registered in the respective names of the beneficial holders 
          thereof, and thereafter shall be transferable without restriction, if:

               (A)  The Depositary, or any successor securities depositary,
               shall have notified the Company and the Trustee that it is
               unwilling or unable to continue to act as securities depositary
               with respect to such Security of Series No. 4 or the Company
               becomes aware that the Depositary has ceased to be a clearing
               agency registered under the Securities Exchange Act of 1934, as
               amended, and, in any such case, the Trustee shall not have been
               notified by the Company within ninety (90) days of the identity
               of a successor securities depositary with respect to such
               Security of Series No. 4;

               (B)  The Company shall have delivered to the Trustee a Company
               Order to the effect that such Security of Series No. 4 shall be
               so exchangeable on and after a date specified therein; or

               (C)(1) an Event of Default shall have occurred and be continuing,
               (2) the Trustee shall have given notice of such Event of Default
               pursuant to Section 1102 of the Original Indenture and (3) there
               shall have been delivered to the Company and the Trustee an 
               Opinion of Counsel to the effect that the interests of the 
               beneficial owners of such Security of Series No. 4 in respect
               thereof will be materially impaired unless such owners become 
               Holders of certificated notes.

     (r)  not applicable;

     (s)  no service charge shall be made for the registration of transfer
     or exchange of any Securities of Series No. 4 provided, however, that
     the Company may require payment of a sum sufficient to cover any tax
     or other governmental charge payable in connection with any such
     exchange or transfer;

     (t)  not applicable;

     (u)  (i) If the Company shall have caused the Company's indebtedness in 
          respect of any Security of Series No. 4 to have been satisfied and 
          discharged prior to the Maturity of such Security of Series No. 4, as
          provided in Section 901 of the Original Indenture, the Company shall,
          promptly after the date of such satisfaction and discharge, give a 
          notice to each Person who was a Holder of any such Security of Series 
          No. 4 on such date stating (A)(1) the aggregate principal amount of 
          such Security of Series No. 4 and (2) the aggregate amount of any 
          money (other than amounts, if any, deposited in respect of accrued 
          interest on such Security of Series No. 4) and the aggregate principal
          amount of, the rate or rates of interest on, and the aggregate fair 
          market value of, any Eligible Obligations deposited pursuant to 
          Section 901 of the Original Indenture with respect to such Security of
          Series No. 4 and (B) that the Company will provide (and the Company 
          shall promptly so provide) to such Person, or any beneficial owner of
          such Security of Series No. 4 holding through such Person (upon 
          written request to the Company sent to an address specified in such
          notice), such other information as such Person or beneficial owner, as
          the case may be, reasonably may request in order to enable it to 
          determine the federal income tax 

                                      5 
<PAGE>

          consequences to it resulting from the satisfaction and discharge 
          of the Company's indebtedness in respect of such Security of 
          Series No. 4.  Thereafter, the Company shall, within forty-five (45)
          days after the end of each calendar year, give to each Person who at
          any time during such calendar year was a Holder of such Security of 
          Series No. 4 a notice containing (X) such information as may be 
          necessary to enable such Person to report its income, gain or loss
          for federal income tax purposes with respect to such Security of
          Series No. 4 or the assets held on deposit in respect thereof during
          such calendar year or the portion thereof during which such Person was
          a Holder of such Security of Series No. 4, as the case may be (such
          information to be set forth for such calendar year as a whole and for
          each month during such year) and (Y) a statement to the effect that
          the Company will provide (and the Company shall promptly so provide)
          to such Person, or any beneficial owner of such Security of Series No.
          4 holding through such Person (upon written request to the Company
          sent to an address specified in such notice), such other information
          as such Person or beneficial owner, as the case may be, reasonably may
          request in order to enable it to determine its income, gain or loss
          for federal income tax purposes with respect to such Security of
          Series No. 4 or such assets for such year or portion thereof, as the
          case may be.  The obligation of the Company to provide or cause to be
          provided information for purposes of income tax reporting by any
          Person as described in the first two sentences of this paragraph shall
          be deemed to have been satisfied to the extent that the Company has
          provided or caused to be provided substantially comparable information
          pursuant to any requirements of the Internal Revenue Code of 1986, as
          amended from time to time (the "Code"), and United States Treasury
          regulations thereunder.

          (ii)   Notwithstanding the provisions of subparagraph (i) above,
          the Company shall not be required to give any notice specified in
          such subparagraph or to otherwise furnish any of the information
          contemplated therein if the Company shall have delivered to the
          Trustee an Opinion of Counsel to the effect that the Holder of
          such Security of Series No. 4 will not recognize income, gain or
          loss for federal income tax purposes as a result of the
          satisfaction and discharge of the Company's indebtedness in
          respect of such Security of Series No. 4 and such Holder will be
          subject to federal income taxation on the same amounts and in the
          same manner and at the same times as if such satisfaction and
          discharge had not occurred.

          (iii)  Anything in this clause (u) to the contrary notwithstanding,
          the Company shall not be required to give any notice specified in
          subparagraph (i) or to otherwise furnish the information 
          contemplated therein or to deliver any Opinion of Counsel contemplated
          by subparagraph (ii) if the Company shall have caused the applicable
          Security of Series No. 4 to be deemed to have been paid for purposes
          of the Indenture, as provided in Section 901 of the Original 
          Indenture, but shall not have effected the satisfaction and discharge
          of its indebtedness in respect of such Security of Series No. 4 
          pursuant to such Section. 

     (v)  each Security of Series No. 4 shall be substantially in the form
     attached as Exhibit A hereto and shall have such further terms as are
     set forth in such form.


                                      6

<PAGE>

                                   ARTICLE TWO

                            MISCELLANEOUS PROVISIONS

     This Supplemental Indenture No. 5 is a supplement to the Original
Indenture.  As previously supplemented and further supplemented by this
Supplemental Indenture No. 5, the Original Indenture is in all respects
ratified, approved and confirmed, and the Original Indenture, all previous
supplements thereto and this Supplemental Indenture No. 5 shall together
constitute one and the same instrument.











                                      7

<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture No. 5 to be duly executed as of the day and year first above written.

                                   PUBLIC SERVICE COMPANY OF
                                           COLORADO


                                   By:  /s/  R. C. KELLY                      
                                        ------------------------------------- 
                                        R. C. Kelly
                                        Senior Vice President, Treasurer,
                                          and Chief Financial Officer



                                   FIRST TRUST OF NEW YORK,
                                     NATIONAL ASSOCIATION, Trustee


                                   By:  /s/  CATHERINE F. DONOHUE
                                        ------------------------------------- 
                                        Catherine F. Donohue
                                        Vice President








                                      8 
<PAGE>


STATE OF COLORADO         )
                          ) ss.:
CITY AND COUNTY OF DENVER )


          On the 8th day of November, 1996, before me personally came R. C.
Kelly, to me known, who, being by me duly sworn, did depose and say that he is a
Senior Vice President of Public Service Company of Colorado, one of the
corporations described in and which executed the foregoing instrument; and that
he signed his name thereto by authority of the Board of Directors of said
corporation.


                                       /s/  JO LYNN R. RIFE 
                                       ---------------------------------------
                                       Jo Lynn R. Rife
                                       Notary Public, State of Colorado
                                       Commission Expires April 27, 1998










                                      9 
<PAGE>

STATE OF NEW YORK           )
                            ) ss.:
CITY AND COUNTY OF NEW YORK )


          On the 8th day of November, 1996, before me personally came Catherine
F. Donohue, to me known, who, being by me duly sworn, did depose and say that
she is a Vice President of First Trust of New York, National Association, the
national banking association described in and which executed the foregoing
instrument; and that she signed her name thereto by authority of the Board of
Directors of said national banking association.


                                       /s/  JOANNE E. ILSE 
                                       -------------------------------------- 
                                       Joanne E. Ilse
                                       Notary Public, State of New York
                                       Commission Expires October 4, 1997










                                     10 
<PAGE>

                                                                       EXHIBIT A
                                FORM OF SECURITY


                   (See legend at the end of this Security for
                  restrictions on transfer and change of form)


                       PUBLIC SERVICE COMPANY OF COLORADO


                       Secured Medium-Term Note, Series B
                      (being a First Collateral Trust Bond)

     Original Issue Date:              Regular Record Dates:
     Interest Rate:                    Initial Redemption Date:
     Default Rate:                     Initial Redemption Percentage:
     Stated Maturity:                  Annual Redemption Percentage Reduction
     Interest Payment Dates:           Optional Repayment Dates:
     Addendum Attached
     [ ] Yes                           Other/Additional Provisions:
     [ ] No





                      This Note is not a Discount Security
              within the meaning of the within-mentioned Indenture.


                    -----------------------------------------

Principal Amount                                  Registered No.
$                                                 CUSIP


     PUBLIC SERVICE COMPANY OF COLORADO, a corporation duly organized and
existing under the laws of the State of Colorado (herein called the "Company,"
which term includes any successor corporation under the Indenture referred to
below), for value received, hereby promises to pay to 


                                  , or registered assigns, the principal sum of

Dollars on the Stated Maturity specified above (or any Redemption Date or
Repayment Date as defined below), and to pay interest thereon from the Original
Issue Date specified above or from the most recent Interest Payment Date to
which interest has been paid or duly provided for, semi-annually in arrears on
the Interest Payment Dates specified above in each year, commencing with the
Interest Payment Date next succeeding the Original Issue Date specified above,
and at Maturity, at the Interest Rate per annum 


                                    A-1 
<PAGE>

specified above, computed on the basis of a 360-day year consisting of twelve 
30-day months, until the principal hereof is paid or duly provided for and, 
to the extent that payment of such interest shall be legally enforceable, at 
the Default Rate per annum specified above on any overdue payment of 
principal, premium, if any, and/or interest. The interest so payable, and 
paid or duly provided for, on any Interest Payment Date shall, as provided in 
such Indenture, be paid to the Person in whose name this Note (or one or more 
Predecessor Securities) is registered at the close of business on the Regular 
Record Date specified above (whether or not a Business Day) next preceding 
such Interest Payment Date except that if the Original Issue Date of this 
Note is after a Regular Record Date specified above and before the 
corresponding Interest Payment Date, the first payment of interest on this 
Note shall be made to the Person in whose name this Note (or one or more 
Predecessor Securities) is registered at the close of business on the Regular 
Record Date with respect to the next succeeding Interest Payment Date.  
Notwithstanding the foregoing, interest payable at Maturity shall be paid to 
the Person to whom principal shall be paid. Except as otherwise provided in 
said Indenture, any such interest not so paid or duly provided for shall 
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 Note (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 of which shall be given to Holders of Securities of this 
series not less than 15 days prior to such Special Record Date, or paid in 
such other manner as permitted by the Indenture.

     Notwithstanding the foregoing, if an Addendum is attached hereto or
"Other/Additional Provisions" apply to this Note as specified on the face
hereof, this Note shall be subject to the terms set forth in such Addendum or
such "Other/Additional Provisions".

     Payment of the principal of and premium, if any, on this Note and interest
hereon at Maturity shall be made upon presentation of this Note (and with
respect to any applicable repayment of this Note, a duly completed election form
as contemplated below) at the Corporate Trust Office of First Trust of New York,
National Association, in New York, New York or at such other office or agency as
may be designated for such purpose by the Company from time to time. Payment of
interest on this Note (other than interest at Maturity) shall be made by check
mailed to the address of the Person entitled thereto as such address shall
appear in the Note Register, except that if such Person shall be a securities
depositary, such payment may be made by such other means in lieu of check as
shall be agreed upon by the Company, the Trustee and such Person. Payment of the
principal of and premium, if any, and interest on this Note, as aforesaid, shall
be made in such coin or currency of the United States of America as at the time
of payment shall be legal tender for the payment of public and private debts. 

     This Note is one of a duly authorized issue of securities of the Company
(herein called the "Notes"), issued and issuable in one or more series under and
equally secured by an Indenture, dated as of October 1, 1993 (such Indenture as
originally executed and delivered and as supplemented or amended from time to
time thereafter, together with any constituent instruments establishing the
terms of particular Securities, being herein called the "Indenture"), between
the Company and First Trust of New York, National Association, as successor
trustee (herein called the "Trustee," which term includes any further successor
trustee under the Indenture), to which Indenture and all indentures supplemental
thereto reference is hereby made for a description of the property mortgaged,
pledged and held in trust, the nature and extent of the security and the
respective rights, limitations of rights, duties and immunities of the Company,
the Trustee and the Holders of the Securities thereunder and of the terms and
conditions upon which the Securities are, and are to be, authenticated and
delivered and secured. The acceptance of this Note shall be deemed to constitute
the consent and agreement by the Holder hereof to all of the terms and
provisions of the Indenture. This Note is one of the series designated above. 


                                    A-2

<PAGE>

     If any Interest Payment Date, any Redemption Date or the Stated Maturity
shall not be a Business Day (as hereinafter defined), payment of the amounts due
on this Note on such date may be made on the next succeeding Business Day; and,
if such payment is made or duly provided for on such Business Day, no interest
shall accrue on such amounts for the period from and after such Interest Payment
Date, Redemption Date or Stated Maturity, as the case may be, to such Business
Day.

     Unless otherwise specified in an Addendum attached hereto, this Note shall
not be subject to any sinking fund or other mandatory redemption and, unless
otherwise specified on the face hereof in accordance with the provisions of the
following four paragraphs, this Note is not subject to optional redemption or
repayment prior to the Stated Maturity hereof.

     This Note is subject to redemption at the option of the Company at any time
on or after the Initial Redemption Date,  if any, specified on the face hereof,
as a whole at any time or from time to time in part, in increments of $1,000
(provided that any remaining principal amount hereof shall be at least
$100,000), at the Redemption Price (as defined below), plus unpaid accrued
interest hereon to the date fixed for redemption (each, a "Redemption Date"). 
The "Redemption Price" shall initially be the Initial Redemption Percentage
specified on the face hereof multiplied by the unpaid principal amount of this
Note to be redeemed.  The Initial Redemption Percentage shall decline at each
anniversary of the Initial Redemption Date by the Annual Redemption Percentage,
if any, specified on the face hereof until the Redemption Price is 100% of the
unpaid principal amount to be redeemed.

     Notice of redemption shall be given by mail to the Holder of this Note, not
less than 30 days nor more than 60 days prior to the date fixed for redemption,
all as provided in the Indenture. As provided in the Indenture, notice of
redemption at the election of the Company as aforesaid may state that such
redemption shall be conditional upon the receipt by the Paying Agent or Agents
for this Note, on or prior to the date fixed for such redemption, of money
sufficient to pay the principal of and premium, if any, and interest, on this
Note; a notice of redemption so conditioned shall be of no force or effect if
such money is not so received and, in such event, the Company shall not be
required to redeem this Note.

     In the event of redemption of this Note in part only, a new Note or Notes
of this series, of like tenor, for the unredeemed portion hereof and otherwise
having the same terms as this Note will be issued in the name of the Holder
hereof upon the cancellation hereof.

     This Note will be subject to repayment by the Company at the option of the
Holder hereof on the Optional Repayment Date(s), if any, specified on the face
hereof, in whole or in part in increments of $1,000 (provided that any remaining
principal amount hereof shall be at least $100,000), at a repayment price equal
to 100% of the unpaid principal amount to be repaid, plus unpaid interest
accrued hereon to the date fixed for repayment (each a "Repayment Date").  For
this Note to be repaid, this Note must be received not more than 60 nor less
than 30 calendar days prior to the Repayment Date, together with the form hereon
entitled "Option to Elect Repayment" duly completed, by the Trustee at its
Corporate Trust Office in New York, New York or such other office or agency as
may be designated by the Company from time to time.  Exercise of such repayment
option by the Holder hereof will be irrevocable.  In the event of repayment of
this Note in part only, a new Note or Notes of like tenor for the unrepaid
portion hereof and otherwise having the same terms as this Note will be issued
in the name of the Holder hereof upon the cancellation hereof.

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


                                    A-3

<PAGE>

     The Indenture permits, with certain exceptions as therein provided, the
Trustee to enter into one or more supplemental indentures for the purpose of
adding any provisions to, or changing in any manner or eliminating any of the
provisions of, the Indenture with the consent of the Holders of not less than a
majority in aggregate principal amount of the Securities of all series then
Outstanding under the Indenture, considered as one class; provided, however,
that if there shall be Securities of more than one series Outstanding under the
Indenture and if a proposed supplemental indenture shall directly affect the
rights of the Holders of Securities of one or more, but less than all, of such
series, then the consent only of the Holders of a majority in aggregate
principal amount of the Outstanding Securities of all series so directly
affected, considered as one class, shall be required; and provided, further,
that if the Securities of any series shall have been issued in more than one
Tranche and if the proposed supplemental indenture shall directly affect the
rights of the Holders of Securities of one or more, but less than all, of such
Tranches, then the consent only of the Holders of a majority in aggregate
principal amount of the Outstanding Securities of all Tranches so directly
affected, considered as one class, shall be required; and provided, further,
that the Indenture permits the Trustee to enter into one or more supplemental
indentures for limited purposes without the consent of any Holders of
Securities. The Indenture also contains provisions permitting the Holders of a
majority in principal amount of the Securities then Outstanding, on behalf of
the Holders of all Securities, 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 Note shall
be conclusive and binding upon such Holder and upon all future Holders of this
Note and of any Note 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 Note. 

     As provided in the Indenture and subject to certain limitations therein set
forth, this Note or any portion of the principal amount hereof will be deemed to
have been paid for all purposes of the Indenture and to be no longer Outstanding
thereunder, and, at the election of the Company, the Company's entire
indebtedness in respect thereof will be satisfied and discharged, if there has
been irrevocably deposited with the Trustee or any Paying Agent (other than the
Company), in trust, money in an amount which will be sufficient and/or Eligible
Obligations, the principal of and interest on which when due, without regard to
any reinvestment thereof, will provide moneys which, together with moneys so
deposited, will be sufficient, to pay when due the principal of and premium, if
any, and interest on this Note when due.  

     As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Note is registrable in the Security Register, upon
surrender of this Note for registration of transfer at the Corporate Trust
Office of First Trust of New York, National Association, in New York, New York
or such other office or agency as may be designated by the Company from time to
time, 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 of authorized denominations and of like
tenor and aggregate principal amount, will be issued to the designated
transferee or transferees. 

     The Notes are issuable only as registered Notes, without coupons, and in
denominations of $100,000 and in any greater amount in integral multiples of
$1,000.  As provided in the Indenture and subject to certain limitations therein
set forth, the Notes are exchangeable for a like aggregate principal amount of
Notes of the same series and Tranche, of any authorized denominations, as
requested by the Holder surrendering the same, and of like tenor upon surrender
of the Note or Notes to be exchanged at the Corporate Trust Office of First
Trust of New York, National Association, in New York, New York or such other
office or agency as may be designated by the Company from time to time. 


                                    A-4

<PAGE>

     The Company shall not be required to execute or provide for the
registration of transfer of or the exchange of this Note during a period of 15
days immediately preceding the date notice is given calling this Note or any
part hereof for redemption, except with respect to the unredeemed portion of any
Note being redeemed in part.

     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 Note 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 Note is registered as the absolute owner hereof for
all purposes, whether or not this Note be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary. 

     The Indenture and this Note shall be governed by and construed in
accordance with the laws of the State of New York. 

     As used herein "Business Day" means any day, other than a Saturday or
Sunday, which is not a day on which banking institutions or trust companies in
The City of New York, New York or other city in which is located any office or
agency maintained for the payment of the principal of, or premium, if any, or
interest on this Note, are generally authorized or required by law, regulation
or executive order to remain closed. All other terms used in this Note which are
defined in the Indenture shall have the meanings assigned to them in the
Indenture. 

     As provided in the Indenture, no recourse shall be had for the payment of
the principal of, premium, if any, or interest on any Securities, or any part
thereof, or for any claim based thereon or otherwise in respect thereof, or of
the indebtedness represented thereby, or upon any obligation, covenant or
agreement under the Indenture, against, and no personal liability whatsoever
shall attach to, or be incurred by, any incorporator, shareholder, officer or
director, as such, past, present or future of the Company or of any predecessor
or successor corporation (either directly or through the Company or a
predecessor or successor corporation), whether by virtue of any constitutional
provision, statute or rule of law, or by the enforcement of any assessment or
penalty or otherwise; it being expressly agreed and understood that the
Indenture and all the Securities are solely corporate obligations and that any
such personal liability is hereby expressly waived and released as a condition
of, and as part of the consideration for, the execution of the Indenture and the
issuance of the Securities. 

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


                                    A-5

<PAGE>

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed under its corporate seal to be hereunto affixed and attested.

                                       PUBLIC SERVICE COMPANY OF COLORADO



                                       By:
                                          -----------------------------------
                                                 Senior Vice President


Attest:

------------------------
     Secretary


                          CERTIFICATE OF AUTHENTICATION

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

Dated: ___________________

FIRST TRUST OF NEW YORK,             OR          FIRST TRUST OF NEW YORK, 
NATIONAL ASSOCIATION                             NATIONAL ASSOCIATION,
  AS TRUSTEE                                     AS TRUSTEE



By:                                              BY: [                  ],
    ------------------------                          AS AUTHENTICATING AGENT
    Authorized Officer

                                                 By:
                                                    --------------------------
                                                        Authorized Officer

     UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE COMPANY OR ITS
AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND ANY 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 INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

     THIS NOTE MAY NOT BE TRANSFERRED OR EXCHANGED, NOR MAY ANY PURPORTED
TRANSFER BE REGISTERED, EXCEPT (i) THIS NOTE MAY BE TRANSFERRED IN WHOLE, AND
APPROPRIATE REGISTRATION OF TRANSFER EFFECTED, IF SUCH TRANSFER IS BY CEDE &
CO., AS NOMINEE FOR THE DEPOSITORY TRUST COMPANY (THE "DEPOSITARY"), TO THE
DEPOSITARY, OR BY THE DEPOSITARY TO ANOTHER NOMINEE THEREOF, OR BY ANY NOMINEE
OF THE DEPOSITARY TO ANY OTHER NOMINEE THEREOF, OR BY THE DEPOSITARY OR ANY
NOMINEE THEREOF TO ANY SUCCESSOR SECURITIES DEPOSITARY OR ANY NOMINEE THEREOF;
AND (ii) THIS NOTE MAY BE EXCHANGED FOR DEFINITIVE NOTES REGISTERED IN THE
RESPECTIVE NAMES OF THE BENEFICIAL HOLDERS HEREOF, AND THEREAFTER SHALL BE
TRANSFERABLE WITHOUT RESTRICTIONS IF: (A) THE DEPOSITARY, OR ANY SUCCESSOR
SECURITIES DEPOSITARY, SHALL HAVE NOTIFIED THE COMPANY AND THE TRUSTEE THAT IT
IS UNWILLING OR UNABLE TO CONTINUE TO ACT AS SECURITIES DEPOSITARY WITH RESPECT
TO THIS NOTE OR THE COMPANY BECOMES AWARE THAT THE DEPOSITARY HAS CEASED TO BE A
CLEARING AGENCY REGISTERED UNDER THE SECURITIES EXCHANGE ACT OF 1934, 

                                    A-6

<PAGE>

AS AMENDED, AND IN ANY SUCH CASE THE TRUSTEE SHALL NOT HAVE BEEN NOTIFIED BY 
THE COMPANY WITHIN NINETY (90) DAYS OF THE IDENTITY OF A SUCCESSOR SECURITIES 
DEPOSITARY WITH RESPECT TO THIS NOTE; (B) THE COMPANY SHALL HAVE DELIVERED TO 
THE TRUSTEE AN OFFICER'S CERTIFICATE TO THE EFFECT THAT THIS NOTE SHALL BE SO 
EXCHANGEABLE ON AND AFTER A DATE SPECIFIED THEREIN; OR (C)(1) AN EVENT OF 
DEFAULT SHALL HAVE OCCURRED AND BE CONTINUING, (2) THE TRUSTEE SHALL HAVE 
GIVEN NOTICE OF SUCH EVENT OF DEFAULT PURSUANT TO SECTION 1102 OF THE 
INDENTURE AND (3) THERE SHALL HAVE BEEN DELIVERED TO THE COMPANY AND THE 
TRUSTEE AN OPINION OF COUNSEL TO THE EFFECT THAT THE INTERESTS OF THE 
BENEFICIAL OWNERS OF THIS NOTE IN RESPECT THEREOF WILL BE MATERIALLY IMPAIRED 
UNLESS SUCH OWNERS BECOME HOLDERS OF DEFINITIVE NOTES.

                              ____________________

     FOR VALUE RECEIVED the undersigned hereby sells, assigns and transfers unto


--------------------------------------------------------------------------------
    [please insert social security or other identifying number of assignee]


--------------------------------------------------------------------------------
            [please print or typewrite name and address of assignee]


--------------------------------------------------------------------------------
the within Note of PUBLIC SERVICE COMPANY OF COLORADO and does hereby
irrevocably constitute and appoint ________________________________________ , 
Attorney, to transfer said Note on the books of the within-mentioned Company, 
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 Note in every particular without alteration 
or enlargement or any change whatsoever.

                                      A-7 
<PAGE>

                            OPTION TO ELECT REPAYMENT

     The undersigned hereby irrevocably request(s) and instruct(s) the 
Company to repay this Note (or portion hereof specified below) pursuant to 
its terms at a price equal to 100% of the principal amount to be repaid, 
together with unpaid interest accrued hereon to the Repayment Date, to the 
undersigned, at ______________________________________________________________
         (Please print or typewrite name and address of the undersigned)

     For this Note to be repaid, the Trustee must receive at its Corporate Trust
Office in New York, New York not more than 60 nor less than 30 calendar days
prior to the Repayment Date, this Note with this "Option to Elect Repayment"
form duly completed.

     If less than the entire principal amount of this Note is to be repaid,
specify the portion hereof (which shall be increments of $1,000 (provided that
any remaining principal amount hereof shall be at least $100,000)) which the
Holder elects to have repaid and specify the denomination or denominations
(which shall be a minimum of $100,000) of the Notes to be issued to the Holder
for the portion of this Note not being repaid (in the absence of any such
specification, one such Note will be issued for the portion not being repaid).

Principal Amount
to be Repaid:  $           
                ----------         -------------------------------------------- 
Date:                              NOTICE:  The signature(s) on this Option to 
     ---------------------         Elect Repayment must correspond with the 
                                   name(s) as written upon the face of this 
                                   Note in every particular, without alteration
                                   or enlargement or any change whatsoever.



















                                     A-8 
<PAGE>

                                                                      SCHEDULE A

                             SUPPLEMENTAL INDENTURES

<TABLE>

   DATE OF                                                                  PRINCIPAL  
SUPPLEMENTAL                                               PRINCIPAL         AMOUNT    
  INDENTURE               SERIES OF BONDS                AMOUNT ISSUED     OUTSTANDING 
------------              ---------------                -------------     ----------- 
<S>                       <C>                            <C>               <C>         
November 1, 1993           Series No. 1                  $134,500,000     $134,500,000 

January 1, 1994      Series No. 2 due 2001 and           $102,667,000     $102,667,000 
                      Series No. 2 due 2024              $110,000,000     $110,000,000 

September 2, 1994         Appointment of                         None             None 
                        Successor Trustee 

May 1, 1996           Series No. 3 due 2006              $125,000,000     $125,000,000 
</TABLE>

                                    I-1