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


                      PUBLIC SERVICE COMPANY OF NEW MEXICO


                                       TO


                            THE CHASE MANHATTAN BANK


                                     Trustee


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

                          FIRST SUPPLEMENTAL INDENTURE


                           Dated as of August 1, 1998


                                       To


                                    INDENTURE


                           Dated as of August 1, 1998



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

                                  Providing for


                 7.10% Series A Senior Unsecured Notes Due 2005


                                       and


                 7.50% Series B Senior Unsecured Notes Due 2018


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





FIRST SUPPLEMENTAL INDENTURE, dated as of August 1, 1998, between PUBLIC SERVICE
COMPANY OF NEW MEXICO,  a corporation duly organized and existing under the laws
of the State of New Mexico (herein called the  "Company"),  having its principal
office  at  Alvarado  Square,  Albuquerque,  New  Mexico  87158,  and THE  CHASE
MANHATTAN  BANK, a New York banking  corporation,  as Trustee (herein called the
"Trustee") under the Indenture,  dated as of August 1, 1998, between the Company
and the Trustee (the "Indenture").


                             RECITALS OF THE COMPANY

         The Company has executed and  delivered the Indenture to the Trustee to
provide for the issuance  from time to time of its senior  notes (the  "Notes"),
said Notes to be issued in one or more series as in the Indenture provided.

         Pursuant to the terms of the Indenture,  the Company desires to provide
for the establishment of two new series of its Notes to be known,  respectively,
as its 7.10% Series A Senior Unsecured Notes Due 2005 (herein called the "Series
A Notes") and 7.50% Series B Senior  Unsecured Notes Due 2018 (herein called the
"Series  B Notes"  and,  together  with the  Series A Notes,  the  "1998  Senior
Notes"),  the form and  substance  of such  1998  Senior  Notes  and the  terms,
provisions,  and conditions thereof to be set forth as provided in the Indenture
and this First Supplemental Indenture.

         All things necessary to make this First Supplemental  Indenture a valid
agreement of the Company,  and to make the 1998 Senior  Notes,  when executed by
the  Company  and  authenticated  and  delivered  by  the  Trustee,   the  valid
obligations of the Company, have been done.

         NOW, THEREFORE, THIS FIRST SUPPLEMENTAL INDENTURE WITNESSETH:

         For and in consideration of the premises and the purchase of the Series
A Notes by the Holders  thereof,  and the  purchase of the Series B Notes by the
Holders  thereof,  and for the  purpose of setting  forth,  as  provided  in the
Indenture,  the form and  substance  of the 1998  Senior  Notes  and the  terms,
provisions,  and conditions  thereof,  it is mutually agreed,  for the equal and
proportionate  benefit of all Holders of the Series A Notes,  in the case of the
Series A Notes,  and for the equal and  proportionate  benefit of all Holders of
the Series B Notes, in the case of the Series B Notes, as follows:


                                   ARTICLE I

                         GENERAL TERMS AND CONDITIONS OF
                              THE 1998 SENIOR NOTES


         Section 1.01    There  shall  be  and are hereby  authorized two series
of Notes  designated,  respectively,  the "7.10% Series A Senior Unsecured Notes
Due 2005" and the "7.50% Series B Senior Unsecured Notes Due 2018". The Series A
Notes shall be limited in aggregate principal amount to $300,000,000. The Series
A Notes shall mature and the principal thereof shall be due and payable together
with all accrued  and unpaid  interest  thereon on August 1, 2005.  The Series B
Notes shall be limited in aggregate principal amount to $135,000,000. The Series
B Notes shall mature and the principal thereof shall be due and payable together
with all accrued and unpaid interest thereon on August 1, 2018.


                                       



         Section 1.02    The  1998  Senior  Notes  shall  be  issued  in  fully 
registered  form without  coupons,  initially as one or more Global Notes to and
registered  in the  name of  Cede & Co.,  as  nominee  of The  Depository  Trust
Company,  as  Depositary  therefor.  Any  1998  Senior  Notes  to be  issued  or
transferred to, or to be held by, Cede & Co. (or any successor thereof) for such
purpose shall bear the depositary  legend in substantially the form set forth in
the second  paragraph  at the top of the form of 1998  Senior Note in Article II
hereof (in addition to that set forth in Section 2.04 of the Indenture),  unless
otherwise  agreed by the Company,  such  agreement to be confirmed in writing to
the  Trustee.  Each such Global Note may be  exchanged in whole or in part for a
1998 Senior Note of the same series registered,  and any transfer of such Global
Note in  whole  or in part may be  registered,  in the name or names of  Persons
other than such Depositary or a nominee thereof only under the circumstances set
forth in Clause (2) of the last paragraph of Section 3.05 of the  Indenture,  or
such other  circumstances in addition to or in lieu of those set forth in Clause
(2) of the last  paragraph  of  Section  3.05 of the  Indenture  as to which the
Company shall agree, such agreement to be confirmed in writing to the Trustee.


         Section 1.03    Each  Series A Note will bear  interest  at the rate of
7.10% per annum from  August 6, 1998 or from the most  recent  Interest  Payment
Date (as  hereinafter  defined) to which interest has been paid or duly provided
for,  payable  semi-annually  on  February  1 and August 1 in each year (each an
"Interest  Payment  Date"),  commencing  February 1, 1999,  until the  principal
thereof is paid or made  available  for  payment.  Each  Series B Note will bear
interest  at the rate of 7.50%  per annum  from  August 6, 1998 or from the most
recent  Interest  Payment Date to which  interest has been paid or duly provided
for,  payable  semi-annually  on  each  Interest  Payment  Date  in  each  year,
commencing  February  1,  1999,  until  the  principal  thereof  is paid or made
available for payment.  The interest so payable on a Series A Note or a Series B
Note, as applicable,  and punctually  paid or duly provided for, on any Interest
Payment Date will, as provided in the Indenture,  be paid to the Person in whose
name such Series A Note or Series B Note, as the case may be, or any Predecessor
Note is registered at the close of business on the Regular  Record Date for such
interest,  which  shall be the  January 15 or July 15 (whether or not a Business
Day), as the case may be, next  preceding  such Interest  Payment Date. Any such
installment  of  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 such  Series A Note or Series B Note,
as the  case may be,  or any  Predecessor  Note 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 the Series
A Notes or the  Series B Notes,  as the case may be, not less than 10 days prior
to such  Special  Record  Date,  or may be paid at any time in any other  lawful
manner not  inconsistent  with the  requirements  of any securities  exchange on
which the  Series A Notes or Series B Notes,  as the case may be, may be listed,
and upon such  notice as may be  required  by such  exchange,  all as more fully
provided in the Indenture.

                                       2


         The amount of interest  payable on the 1998 Senior Notes for any period
will be computed on the basis of a 360-day year of twelve 30-day months.  In the
event that any Interest Payment Date,  Redemption Date or Stated Maturity of any
1998 Senior Note is not a Business  Day,  then  payment of interest or principal
(and premium,  if any) payable on such date will be made on the next  succeeding
day which is a  Business  Day (and  without  any  interest  or other  payment in
respect  of any such  delay),  in each case with the same force and effect as if
made on such Interest Payment Date,  Redemption Date or Stated Maturity,  as the
case may be.

         As used herein,  a "Business  Day" means any day, other than a Saturday
or Sunday,  which is not a day on which banking institutions in the State of New
York or The City of New York are  authorized or obligated by law,  regulation or
executive order to close.

         Section 1.04    Payment of the principal  of, and premium,  if any, and
interest on the Series A Notes and on the Series B Notes  shall be payable,  and
registration  of transfer  and  exchanges of the Series A Notes and the Series B
Notes may be effected, and notices and demands to or upon the Company in respect
of the Series A Notes, the Series B Notes and the Indenture may be served at the
office or agency of the  Company  maintained  for that  purpose  in The City and
State of New York,  which shall be the Corporate  Trust Office of the Trustee or
at such other  office or agency in The City of New York and State of New York as
may be  designated  for such purpose by the Company from time to time;  and such
payment  shall be made in such coin or currency of the United  States of America
as at the time of payment  is legal  tender  for  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 Note Register.

         Section 1.05    The Company, at its option, may redeem at any time all,
or, from time to time, any part of the Series A Notes and/or the Series B Notes,
upon notice as provided  in the  Indenture  (except  that,  notwithstanding  the
provisions of Section 11.04 of the  Indenture,  any notice of redemption for the
1998  Series  Notes  given  pursuant  to said  Section  need not set  forth  the
Redemption  Price but only the manner of  calculation  thereof) at a  Redemption
Price equal to the greater of (i) 100% of their principal amount or (ii) the sum
of the present  values of the  remaining  scheduled  payments of  principal  and
interest  thereon  discounted  to the  Redemption  Date  on a  semiannual  basis
(assuming a 360-day year  consisting  of twelve  30-day  months) at the Treasury
Yield plus 50 basis points, plus in each case accrued interest to the Redemption
Date,  such  Redemption  Price  to be  set  forth  in an  Officers'  Certificate
delivered  to the  Trustee on or before the  Redemption  Date and upon which the
Trustee may conclusively rely.

         For purposes of this Section 1.05,  the following  terms shall have the
following meanings:

         "Treasury  Yield" means,  with respect to any Redemption Date, the rate
per annum equal to the semiannual 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.


                                       3


         "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 series of 1998 Senior Notes being redeemed 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 such series of 1998 Senior Notes. "Independent
Investment  Banker" means Salomon  Brothers Inc or, if such firm is unwilling or
unable to select the Comparable  Treasury Issue, one of the remaining  Reference
Treasury Dealers appointed by the Trustee after consultation with the Company.

         "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 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 (ii) if such release (or any successor release) is not
published or does not contain such prices on such  Business Day, (A) the average
of the Reference  Treasury  Dealer  Quotations for such Redemption  Date,  after
excluding the highest and lowest such Reference  Treasury Dealer  Quotations for
such  Redemption  Date,  or (B) if the  Trustee  obtains  fewer  than  four such
Reference  Treasury  Dealer  Quotations,  the  average  of all such  Quotations.
"Reference  Treasury  Dealer  Quotations"  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 5:00 p.m. on the
third Business Day preceding such Redemption Date.

         "Reference  Treasury  Dealer"  means (i) each of Salomon  Brothers Inc,
Chase Securities Inc., Morgan Stanley & Co.  Incorporated,  Citicorp Securities,
Inc., J.P.  Morgan  Securities  Inc.,  BancAmerica  Robertson  Stephens and CIBC
Oppenheimer Corp.;  provided,  however, that if any of the foregoing shall cease
to be a primary U.S.  Government  securities dealer in New York City (a "Primary
Treasury  Dealer"),  the  Company  shall  substitute  therefor  another  Primary
Treasury  Dealer;  and (ii) any other Primary  Treasury  Dealer  selected by the
Company.

         If less than all of the 1998  Senior  Notes of either  series are to be
redeemed,  the Trustee shall select, in such manner as it shall deem appropriate
and fair, the particular  1998 Senior Notes or portions  thereof to be redeemed.
Notice  of  redemption  shall be given by mail not less than 30 nor more than 60
days prior to the  Redemption  Date to the  Holders of 1998  Senior  Notes to be
redeemed  (which,  as long as the 1998 Senior  Notes are held in the  book-entry
only  system,  will  be The  Depository  Trust  Company  (or its  nominee)  or a
successor  Depositary);  provided,  however,  that the failure to duly give such
notice by mail,  or any defect  therein,  shall not affect the  validity  of any
proceedings for the redemption of 1998 Senior Notes as to which there shall have
been no such failure or defect. Such notice may state that such redemption shall
be  conditional  upon receipt by the Paying Agent or Agents for such 1998 Senior
Notes,  on or prior to the  Redemption  Date,  of  money  sufficient  to pay the
principal of and premium,  if any, and interest,  if any, on such Notes and that
if such money shall not have been so received  such notice  shall be of no force
or effect and the Company  shall not be  required  to redeem such Notes.  On and
after the  Redemption  Date (unless the Company  shall default in the payment of
the  series of 1998  Senior  Notes or  portions  thereof to be  redeemed  at the
applicable  Redemption  Price,  together with interest  accrued  thereon to such
date),  interest on the series of 1998 Senior Notes or the  portions  thereof so
called for redemption shall cease to accrue.

                                       4



         The Trustee  shall be under no duty to inquire into,  may  conclusively
presume  the  correctness  of, and shall be fully  protected  in acting upon the
Company's calculation of any Redemption Price.

         The Company shall give to the Trustee  written notice of the Redemption
Price  applicable  to the  Series A Notes or the Series B Notes  promptly  after
calculation thereof.

         The 1998 Senior Notes will not be subject to any sinking fund.


         Section 1.06    The Series A  Notes  shall  be  defeasible  pursuant to
Section  13.02 and Section 13.03 of the  Indenture.  The Series B Notes shall be
defeasible pursuant to Section 13.02 and Section 13.03 of the Indenture.


                                   ARTICLE II

                            FORM OF 1998 SENIOR NOTES


         Section 2.01    The Series  A  Notes  and  the  Series B  Notes and the
Trustee's  certificate  of  authentication  to be  endorsed  thereon  are  to be
substantially  in the following form (where  bracketed  material appears in said
form of Note, the material in the first set of brackets  relates to the Series A
Notes and the  material  in the second set of  brackets  relates to the Series B
Notes):

         Form of 1998 Senior Note.

THIS NOTE IS A GLOBAL  NOTE  WITHIN  THE  MEANING OF THE  INDENTURE  HEREINAFTER
REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE  THEREOF.
THIS NOTE MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR A NOTE REGISTERED, AND NO
TRANSFER OF THIS NOTE IN WHOLE OR IN PART MAY BE REGISTERED,  IN THE NAME OF ANY
PERSON OTHER THAN SUCH  DEPOSITARY OR A NOMINEE  THEREOF,  EXCEPT IN THE LIMITED
CIRCUMSTANCES DESCRIBED IN THE INDENTURE.

UNLESS THIS  CERTIFICATE  IS PRESENTED BY AN  AUTHORIZED  REPRESENTATIVE  OF THE
DEPOSITARY  TRUST COMPANY,  A NEW YORK  CORPORATION  ("DTC"),  TO PUBLIC SERVICE
COMPANY OF NEW MEXICO 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.

                                       5



         Form of Face of [7.10] [7.50]% Series[A] [B] Senior Unsecured Notes Due
[2005] [2018].

                      PUBLIC SERVICE COMPANY OF NEW MEXICO

     [7.10] [7.50] % Series [A] [B] Senior Unsecured Notes Due [2005] [2018]

No. ________                                                         $________
                                                            CUSIP No. ________

         PUBLIC SERVICE COMPANY OF NEW MEXICO,  a corporation duly organized and
existing under the laws of New Mexico  (herein called the "Company",  which term
includes any successor Person under the Indenture  hereinafter referred to), for
value received,  hereby promises to pay to _________, or registered assigns, the
principal  sum of  ________  Dollars  on August  1,  [2005]  [2018],  and to pay
interest  thereon from August 6, 1998 or from the most recent  Interest  Payment
Date to which  interest has been paid or duly  provided  for,  semi-annually  on
February 1 and August 1 in each year,  commencing  February 1, 1999, at the rate
of  [7.10]  [7.50]%  per  annum,  until  the  principal  hereof  is paid or made
available  for payment.  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 Note (or one or more Predecessor Notes)
is  registered  at the close of  business  on the  Regular  Record Date for such
interest,  which  shall be the  January 15 or July 15 (whether or not a Business
Day), as the case may be, next  preceding  such 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 Note (or one or more Predecessor  Notes) 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 Notes 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 Notes 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
Note will be made at the  office or agency of the  Company  maintained  for that
purpose in The City of New York,  in such coin or currency of the United  States
of America as at the time of payment is legal  tender for  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 Note Register.

         Reference  is hereby  made to the further  provisions  of this Note set
forth on the reverse  hereof,  which further  provisions  shall for all purposes
have the same effect as if set forth at this place.

                                       6


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

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

                                     PUBLIC SERVICE COMPANY OF NEW MEXICO



                                     By:
                                         --------------------------------
                                         [Title]
Attest:



- ------------------------------------
[Title]

         Form of Trustee's Certificate of Authentication.


                         CERTIFICATION OF AUTHENTICATION

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

Dated:                                    THE CHASE MANHATTAN BANK,

                                                               As Trustee



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


Form of Reverse of [7.10]  [7.50]%  Series  [A] [B] Senior  Unsecured  Notes Due
[2005] [2018].

         This  Note is one of a duly  authorized  issue of  senior  notes of the
Company  (herein  called  the  "Notes"),  issued and to be issued in one or more
series  under an  Indenture,  dated as of  August  1, 1998  (herein  called  the
"Indenture",  which  term  shall  have  the  meaning  assigned  to  it  in  such
instrument),  between  the  Company  and The Chase  Manhattan  Bank,  as Trustee
(herein  called the "Trustee",  which term includes any successor  trustee under
the Indenture), and reference is hereby made to the Indenture for a statement of
the respective rights,  limitations of rights,  duties and immunities thereunder
of the  Company,  the Trustee and the Holders of the Notes and of the terms upon
which the Notes are, and are to be,  authenticated  and delivered.  This Note is
one of the series  designated on the face hereof limited in aggregate  principal
amount to $[300,000,000] [135,000,000].


                                       7


         The Company,  at its option, may redeem at any time, all, or, from time
to time,  any part of the Notes of this  series,  upon notice as provided in the
Indenture  (except that  notwithstanding  the provisions of Section 11.04 of the
Indenture,  any notice of  redemption  of the Notes of this  series need not set
forth the  Redemption  Price but only the manner of  calculation  thereof)  at a
Redemption  Price equal to the greater of (i) 100% of their principal  amount or
(ii) the sum of the  present  values  of the  remaining  scheduled  payments  of
principal and interest thereon discounted to the Redemption Date on a semiannual
basis  (assuming  a 360-day  year  consisting  of twelve  30-day  months) at the
Treasury Yield plus 50 basis points,  plus in each case accrued  interest to the
Redemption  Date,  such  Redemption  Price  to be  set  forth  in  an  Officers'
Certificate  delivered to the Trustee on or before the Redemption  Date and upon
which the Trustee may conclusively rely.

         For  purposes of the  foregoing  optional  redemption  provisions,  the
following terms shall have the following meanings:

         "Treasury  Yield" means,  with respect to any Redemption Date, the rate
per annum equal to the semiannual 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.

         "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 of this series 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 of this  series.  "Independent  Investment  Banker"
means Salomon Brothers Inc or, if such firm is unwilling or unable to select the
Comparable  Treasury  Issue,  one of the remaining  Reference  Treasury  Dealers
appointed by the Trustee after consultation with the Company.

         "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 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 (ii) if such release (or any successor release) is not
published or does not contain such prices on such  Business Day, (A) the average
of the Reference  Treasury  Dealer  Quotations for such Redemption  Date,  after
excluding the highest and lowest such Reference  Treasury Dealer  Quotations for
such  Redemption  Date,  or (B) if the  Trustee  obtains  fewer  than  four such
Reference  Treasury  Dealer  Quotations,  the  average  of all such  Quotations.
"Reference  Treasury  Dealer  Quotations"  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 5:00 p.m. on the
third Business Day preceding such Redemption Date.


                                       8


         "Reference  Treasury  Dealer"  means (i) each of Salomon  Brothers Inc,
Chase Securities Inc., Morgan Stanley & Co.  Incorporated,  Citicorp Securities,
Inc., J.P.  Morgan  Securities  Inc.,  BancAmerica  Robertson  Stephens and CIBC
Oppenheimer Corp.;  provided,  however, that if any of the foregoing shall cease
to be a primary U.S.  Government  securities dealer in New York City (a "Primary
Treasury  Dealer"),  the  Company  shall  substitute  therefor  another  Primary
Treasury  Dealer;  and (ii) any other Primary  Treasury  Dealer  selected by the
Company.

         The Trustee  shall be under no duty to inquire into,  may  conclusively
presume  the  correctness  of, and shall be fully  protected  in acting upon the
Company's calculation of any Redemption Price.

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

         In the event of  redemption  of this Note in part  only,  a new Note or
Notes 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 Indenture  contains  provisions  for  defeasance at any time of the
entire indebtedness of this Note or certain restrictive  covenants and Events of
Default with  respect to this Note,  in each case upon  compliance  with certain
conditions set forth in the Indenture.

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

         The Indenture permits, with certain exceptions as therein provided, the
Company and 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 Notes
of all series then  Outstanding  under the  Indenture,  considered as one class;
provided,  however,  that if  there  shall be  Notes  of more  than  one  series
Outstanding under the Indenture and if a proposed  supplemental  indenture shall
directly affect the rights of the Holders of Notes 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  Notes of all series so directly
affected,  considered as one class,  shall be required;  and provided,  further,
that if the Notes 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 Notes 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  Notes of all Tranches so directly  affected,  considered as one
class, shall be required.  The Indenture also contains provisions permitting the
Holders of specified  percentages  in principal  amount of the Notes of each, or
all series, as the case may be, then Outstanding under the Indenture,  on behalf
of the Holders of all Notes of such series,  to waive  compliance by the Company
with certain provisions of the Indenture and permitting the Holders of specified
percentages in principal  amount of the Notes of each series  Outstanding  under
the  Indenture,  on behalf of the Holders of all Notes of such series,  to waive
certain past  defaults  under the Indenture  and their  consequences,  provided,
however,  that if any such past  default  affects more than one series of Notes,
the Holders of a majority in aggregate principal amount of the Outstanding Notes
of all such series,  considered as one class, shall have the right to waive such
past default,  and not the Holders of the Notes of any one such series. 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.


                                       9


         As provided  in and subject to the  provisions  of the  Indenture,  the
Holder of this Note shall not have the right to institute  any  proceeding  with
respect to the Indenture or for the  appointment of a receiver or trustee or for
any other remedy thereunder,  unless such Holder shall have previously given the
Trustee  written  notice of a  continuing  Event of Default  with respect to the
Notes of this  series,  the  Holders  of not less than a majority  in  aggregate
principal  amount of the Notes of all series at the time  Outstanding in respect
of which an Event of Default shall have  occurred and be  continuing  shall have
made written request to the Trustee to institute  proceedings in respect of such
Event of Default as Trustee and offered the Trustee  reasonable  indemnity,  and
the Trustee  shall not have received from the Holders of a majority in principal
amount of Notes of all  series at the time  Outstanding  in  respect of which an
Event of Default shall have occurred and be continuing a direction  inconsistent
with such request,  and shall have failed to institute any such proceeding,  for
60 days after  receipt  of such  notice,  request  and offer of  indemnity.  The
foregoing  shall not apply to any suit instituted by the Holder of this Note for
the  enforcement  of any payment of principal  hereof or any premium or interest
hereon on or after the respective due dates expressed herein.

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

         As provided in the Indenture and subject to certain limitations therein
set forth,  the transfer of this Note is registrable in the Note Register,  upon
surrender of this Note 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 Note are payable,  duly endorsed by, or accompanied by a written instrument
of transfer in form  satisfactory  to the  Company and the Note  Registrar  duly
executed by, the Holder hereof or his attorney duly  authorized in writing,  and
thereupon one or more new Notes 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 Notes 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,
Notes of this series are exchangeable  for a like aggregate  principal amount of
Notes of this series and of like tenor of a different  authorized  denomination,
as requested by the Holder surrendering the same.


                                       10


         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  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.

         As used herein,  a "Business  Day" means any day, other than a Saturday
or Sunday,  which is not a day on which banking institutions in the State of New
York or The City of New York are  authorized or obligated by law,  regulation or
executive order to close. All other terms used in this Note which are defined in
the Indenture shall have the meanings assigned to them in the Indenture.


                                  ARTICLE III

                       ORIGINAL ISSUE OF 1998 SENIOR NOTES


         Section 3.01    Series A  Notes in  the aggregate  principal  amount of
$300,000,000 may, upon execution of this First Supplemental  Indenture,  or from
time to time thereafter,  be executed on behalf of the Company by any officer or
employee  authorized to do so by a Board  Resolution,  under its corporate  seal
affixed thereto or reproduced thereon attested by its Secretary or by one of its
Assistant  Secretaries and delivered to the Trustee for authentication,  and the
Trustee  shall  thereupon  authenticate  and  deliver  said  Series  A Notes  in
accordance with a Company Order delivered to the Trustee by the Company.


         Section 3.02    Series B  Notes  in the  aggregate  principal amount of
$135,000,000 may, upon execution of this First Supplemental  Indenture,  or from
time to time thereafter,  be executed on behalf of the Company by any officer or
employee  authorized to do so by a Board  Resolution,  under its corporate  seal
affixed thereto or reproduced thereon attested by its Secretary or by one of its
Assistant  Secretaries and delivered to the Trustee for authentication,  and the
Trustee  shall  thereupon  authenticate  and  deliver  said  Series  B Notes  in
accordance with a Company Order delivered to the Trustee by the Company.


                                   ARTICLE IV
 
                          PAYING AGENT AND REGISTRAR


         Section 4.01    The Chase  Manhattan  Bank will be the Paying Agent and
Note Registrar for the 1998 Senior Notes.


                                       11



                                   ARTICLE V

                                SUNDRY PROVISIONS


         Section 5.01    Except as otherwise expressly  provided  in this  First
Supplemental  Indenture or in the form of 1998 Senior Notes or otherwise clearly
required by the context hereof or thereof, all terms used herein or in said form
of the 1998  Senior  Notes  that are  defined  in the  Indenture  shall have the
several meanings respectively assigned to them thereby.

         Section 5.02    The  Indenture,   as   supplemented   by   this   First
Supplemental  Indenture,  is in all respects  ratified and  confirmed,  and this
First Supplemental Indenture shall be deemed part of the Indenture in the manner
and to the extent herein and therein provided.

         Section 5.03    The Trustee hereby accepts the trusts herein  declared,
provided, created,  supplemented, or amended and agrees to perform the same upon
the terms and  conditions  herein  and in the  Indenture  set forth and upon the
following terms and conditions:

            The  Trustee  shall  not  be  responsible  in  any  manner
            whatsoever   for  or  in  respect  of  the   validity   or
            sufficiency of this First Supplemental Indenture or for or
            in respect of the recitals  contained herein, all of which
            recitals are made by the Company solely. In general,  each
            and every term and  condition  contained  in Article VI of
            the  Indenture  shall apply to and form part of this First
            Supplemental  Indenture  with the same force and effect as
            if the  same  were  herein  set  forth in full  with  such
            omissions,  variations,  and insertions, if any, as may be
            appropriate  to make the same conform to the provisions of
            this First Supplemental Indenture.


         Section 5.04    This First  Supplemental Indenture may  be  executed in
any number of  counterparts,  each of which so executed shall be deemed to be an
original,  but all such counterparts  shall together  constitute but one and the
same instrument.


                                       12




         IN  WITNESS  WHEREOF,   the  parties  hereto  have  caused  this  First
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 NEW MEXICO



                                        By:
                                            -------------------------------- 
                                            M.H. Maerki
                                            Senior Vice President
                                            and Chief Financial Officer
Attest:



- -----------------------------------
      Assistant Secretary
                                        THE CHASE MANHATTAN BANK, as Trustee



                                        By:
                                            -------------------------------- 
                                            P. Morabito
                                            Vice President
Attest:



- -----------------------------------
      Senior Trust Officer



                                       13




STATE OF NEW MEXICO  )
                     ) ss.:
COUNTY OF BERNALILLO )


         On the ____ day of August, 1998, before me personally came M.H. Maerki,
to me known, who, being by me duly sworn, did depose and say that he is a Senior
Vice  President and Chief  Financial  Officer of Public  Service  Company of New
Mexico,  one of the  corporations  described in and which executed the foregoing
instrument; that he 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 he signed his name thereto
by like authority.


                                            -------------------------------- 
                                                   Notary Public

                                            My Commission Expires:

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

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


         On the ____ day of August, 1998, before me personally came P. Morabito,
to me known,  who, being by me duly sworn, did depose and say that she is a Vice
President of The Chase Manhattan Bank, one of the corporations  described in and
which  executed  the  foregoing  instrument;  that  she  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 she signed her name thereto by like authority.



                                            -------------------------------- 
                                                   Notary Public