Filed Pursuant to Rule 424(b)(5)
                                                 Registration Nos. 333-94277 and
                                                                   333-58445

          PROSPECTUS SUPPLEMENT TO PROSPECTUS DATED JANUARY 21, 2000

                                  $300,000,000
                         ARIZONA PUBLIC SERVICE COMPANY
                         7 5/8% NOTES DUE AUGUST 1, 2005

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

     We will pay  interest  on the notes  each  February 1 and August 1. We will
make the first interest  payment on February 1, 2001. We may redeem the notes at
any time,  if we pay a  "make-whole  premium."  There is no sinking fund for the
notes.  We do not  intend  to list  the  notes  on any  securities  exchange  or
quotation system.

                                                  UNDERWRITING
                                PRICE TO         DISCOUNTS AND        PROCEEDS
                               PUBLIC (1)         COMMISSIONS        TO APS (1)
                              ------------        ----------       ------------
Per Note ..................         99.522%               .6%            98.922%
Total .....................   $298,566,000        $1,800,000       $296,766,000

(1) Plus accrued interest from August 7, 2000.


     Delivery  of the  notes in  book-entry  form  only will be made on or about
August 7, 2000.

     Neither the  Securities and Exchange  Commission  nor any State  Securities
Commission has approved or disapproved of these securities or determined if this
prospectus  supplement or the related  prospectus  is truthful or complete.  Any
representation to the contrary is a criminal offense.

CREDIT SUISSE FIRST BOSTON
                     SALOMON SMITH BARNEY
                                  BANC OF AMERICA SECURITIES LLC
                                                               J.P. MORGAN & Co.

           The date of this Prospectus Supplement is August 2, 2000.

                                TABLE OF CONTENTS

                              PROSPECTUS SUPPLEMENT

                                                                          PAGE
                                                                          ----

APPLICATION OF PROCEEDS .................................................. S-3
TERMS OF THE NOTES ....................................................... S-3
RATIO OF EARNINGS TO FIXED CHARGES ....................................... S-5
REGARDING THE TRUSTEE .................................................... S-5
UNDERWRITING ............................................................. S-5

                                   PROSPECTUS

ABOUT THIS PROSPECTUS ....................................................   3
FORWARD-LOOKING STATEMENTS ...............................................   3
WHERE YOU CAN FIND MORE INFORMATION ......................................   4
BUSINESS OF ARIZONA PUBLIC SERVICE COMPANY ...............................   5
RATIO OF EARNINGS TO FIXED CHARGES .......................................   5
USE OF PROCEEDS ..........................................................   5
DESCRIPTION OF FIRST MORTGAGE BONDS ......................................   5
DESCRIPTION OF DEBT SECURITIES ...........................................   9
GLOBAL SECURITIES ........................................................  15
REGARDING THE TRUSTEES ...................................................  16
PLAN OF DISTRIBUTION .....................................................  17
EXPERTS ..................................................................  17
LEGAL OPINIONS ...........................................................  17

                                   ----------

     YOU  SHOULD  RELY  ONLY ON THE  INFORMATION  CONTAINED  IN THIS  PROSPECTUS
SUPPLEMENT OR TO WHICH WE HAVE REFERRED YOU IN THE ACCOMPANYING  PROSPECTUS.  WE
HAVE NOT AUTHORIZED  ANYONE TO PROVIDE YOU WITH  INFORMATION  THAT IS DIFFERENT.
THIS DOCUMENT MAY ONLY BE USED WHERE IT IS LEGAL TO SELL THESE  SECURITIES.  THE
INFORMATION IN THIS DOCUMENT MAY ONLY BE ACCURATE ON THE DATE OF THIS DOCUMENT.

                                       S-2

                             APPLICATION OF PROCEEDS

     We will use the net proceeds from the sale of the notes:

     *    to repay short-term borrowings (with an estimated average interest
          rate of 6.5%) incurred:
          *    to redeem $75 million of our 10% Monthly Income Debt Securities
               (MIDS) due January 31, 2025 in January 2000:
          *    to redeem $101.5 million of our First Mortgage Bonds, 10.25%
               Series due May 15, 2020, called on May 15, 2000;
          *    to repay a $50 million floating-rate term loan due June 18, 2003
               on June 14, 2000; and
          *    to repay a $10 million collateralized loan bearing interest at
               5.375% at maturity on July 31, 2000; and
     *    to pay at maturity on September 15, 2000 a portion of the $100 million
          that will become due on our First Mortgage Bonds, 5.75% Series due
          2000.

     Until we are able to use the proceeds for these purposes, we will invest
the proceeds temporarily in United States Government or agency obligations,
commercial paper, bank certificates of deposit, or repurchase agreements
collateralized by United States government or agency obligations, or deposit the
proceeds with banks. We will obtain the remaining amount necessary to pay our
First Mortgage Bonds, 5.75% Series due 2000 from cash from operations or
short-term borrowings.

                               TERMS OF THE NOTES

     WE WILL ISSUE THE NOTES AS A SEPARATE SERIES OF DEBT SECURITIES UNDER THE
INDENTURE DATED AS OF JANUARY 15, 1998, BETWEEN US AND THE CHASE MANHATTAN BANK,
AS TRUSTEE. BECAUSE THIS IS A SUMMARY, IT DOES NOT CONTAIN ALL THE INFORMATION
THAT MAY BE IMPORTANT TO YOU. THE FOLLOWING DESCRIPTION OF SPECIFIC TERMS OF THE
NOTES SUPPLEMENTS THE DESCRIPTION OF THE GENERAL TERMS AND PROVISIONS OF THE
DEBT SECURITIES IN THE PROSPECTUS UNDER "DESCRIPTION OF DEBT SECURITIES."

GENERAL

     The specific financial and legal terms of the notes are set forth below:

     *    TITLE: 7 5/8% Notes Due 2005
     *    TOTAL PRINCIPAL AMOUNT BEING ISSUED: $300,000,000
     *    DUE DATE FOR PRINCIPAL: August 1, 2005
     *    INTEREST RATE: 7 5/8%
     *    DATE INTEREST STARTS ACCRUING: August 7, 2000
     *    INTEREST DUE DATES: August 1 and February 1
     *    FIRST INTEREST DUE DATE: February 1, 2001
     *    REGULAR RECORD DATES FOR INTEREST: January 15 for February 1
          interest; July 15 for August 1 interest
     *    COMPUTATION OF INTEREST: on the basis of a 360-day year of twelve
          30-day months
     *    FORM OF NOTES: A Global Security will initially represent the notes.
          We will deposit the Global Security with or on behalf of The
          Depository Trust Company. See "Global Securities" in the prospectus.
          We may allow exchange of the Global Security for registered notes and
          transfer of the Global Security to a person other than DTC in
          additional circumstances that we agree to other than those described
          under that heading.
     *    SINKING FUND: The notes will not be subject to any sinking fund.

     The notes will constitute a series of our unsecured senior Debt Securities.
The notes will rank equally with all of our existing and future senior unsecured
debt and senior to all of our existing and future subordinated debt and will be
effectively subordinated to all of our secured debt. As of June

                                       S-3

30, 2000, we had $900 million of outstanding secured debt. The notes will not
have the benefit of the collateral that secures our First Mortgage Bonds. The
prospectus that accompanies this prospectus supplement describes our Debt
Securities and our First Mortgage Bonds under "Description of Debt Securities"
and "Description of First Mortgage Bonds."

REDEMPTION

     We may redeem all or part of the notes at any time at our option at a
redemption price equal to the greater of (1) the principal amount of the notes
being redeemed plus accrued interest to the redemption date or (2) the
Make-Whole Amount for the notes being redeemed.

     As used herein:

          "MAKE-WHOLE AMOUNT" means the sum, as determined by a Quotation Agent,
     of the present values of the principal amount of the notes to be redeemed,
     together with scheduled payments of interest (exclusive of interest to the
     redemption date) from the redemption date to the maturity date of the
     notes, in each case discounted to the redemption date on a semi-annual
     basis, assuming a 360-day year consisting of twelve 30-day months, at the
     Adjusted Treasury Rate, plus accrued interest on the principal amount of
     the notes being redeemed to the redemption date.

          "ADJUSTED TREASURY RATE" means, with respect to any redemption date,
     (i) the yield, under the heading which represents the average for the
     immediately preceding week, appearing in the most recently published
     statistical release designated "H.15 (519)" or any successor publication
     which is published weekly by the Board of Governors of the Federal Reserve
     System and which establishes yields on actively traded United States
     Treasury securities adjusted to constant maturity under the caption
     "Treasury Constant Maturities," for the maturity corresponding to the
     Comparable Treasury Issue (if no maturity is within three months before or
     after the remaining term of the notes, yields for the two published
     maturities most closely corresponding to the Comparable Treasury Issue
     shall be determined and the Adjusted Treasury Rate shall be interpolated or
     extrapolated from such yields on a straight line basis, rounding to the
     nearest month) or (ii) if such release (or any successor release) is not
     published during the week preceding the calculation date or does not
     contain such yields, the rate per year equal to the semi-annual equivalent
     yield to maturity of the Comparable Treasury Issue, calculated using 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, in each case calculated on the third business day
     preceding the redemption date, plus in each case 0.35%.

          "COMPARABLE TREASURY ISSUE" means the United States Treasury security
     selected by the Quotation Agent as having a maturity comparable to the
     remaining term from the redemption date to the maturity date of the notes
     that would be utilized, at the time of selection and in accordance with
     customary financial practice, in pricing new issues of corporate debt
     securities of comparable maturity to the remaining term of the notes.

          "QUOTATION AGENT" means the Reference Treasury Dealer selected by the
     trustee after consultation with us.

          "REFERENCE TREASURY DEALER" means a primary U.S. Government securities
     dealer selected by us.

          "COMPARABLE TREASURY PRICE" means, with respect to any redemption
     date, if clause (ii) of the definition of Adjusted Treasury Rate is
     applicable, the average of three, or such lesser number as is obtained by
     the trustee, Reference Treasury Dealer Quotations for such redemption date.

          "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., New York City time, on the third business day preceding such
     redemption date.

                                       S-4

          If we elect to redeem all or any part of the notes, we will give
     notice of redemption to holders of the notes. We will give notice of a
     redemption at least 30 days before the redemption date. However, we will
     not know the exact redemption price until 3 business days before the
     redemption date. Therefore, the notice of redemption will only describe how
     the redemption price will be calculated. On the redemption date, if we have
     paid the full redemption price to the trustee, notes called for redemption
     will cease to bear interest and the holders of such notes will only have a
     right to receive payment of the redemption price.

DEFEASANCE

     The provisions described in the prospectus under the caption "Description
of Debt Securities -- Defeasance and Covenant Defeasance" are applicable to the
notes.

                       RATIO OF EARNINGS TO FIXED CHARGES

     The following table sets forth the historical ratio of our earnings to
fixed charges for each of the indicated periods:

              SIX MONTHS
                ENDED                   TWELVE MONTHS ENDED
              ----------      --------------------------------------
               JUNE 30,                     DECEMBER 31,
              ----------      --------------------------------------
                 2000           1999    1998    1997    1996    1995
              ----------      -------   ----    ----    ----    ----
                 3.43         2.05(a)   3.19    3.07    2.84    2.77

     For the purposes of these computations, earnings are defined as the sum of
our pre-tax income plus our fixed charges and the fixed charges of our
subsidiaries. Fixed charges consist of interest on debt, amortization of debt
discount, premium, and expense, and an estimated interest factor in rentals.

- ----------
(a) The ratio for twelve months ended December, 1999 reflects an extraordinary
charge of $140 million for a regulatory disallowance.

                              REGARDING THE TRUSTEE

     The Chase Manhattan Bank is the trustee under the indenture relating to the
notes. We maintain normal banking arrangements with The Chase Manhattan Bank.
The Chase Manhattan Bank also:

     *    serves as trustee for the holders of several series of bonds issued by
          a party unaffiliated with us, secured by, among other things, our
          payments under our Palo Verde Nuclear Generating Station leases;
     *    serves as an issuing and paying agent with respect to our commercial
          paper program; and
     *    has a commitment to lend us up to $34.4 million under a revolving
          credit agreement, none of which was outstanding as of June 30, 2000.

     In addition, an affiliate of The Chase Manhattan Bank is the owner
participant under a trust to which we sold and leased back a portion of Unit 2
of the Palo Verde Nuclear Generating Station.

                                  UNDERWRITING

     Under the terms and subject to the conditions contained in an underwriting
agreement dated August 2, 2000, we have agreed to sell to the underwriters named
below, for whom Credit Suisse First Boston Corporation is acting as
representative, the following respective principal amounts of the notes:

                        UNDERWRITER                       PRINCIPAL AMOUNT
                        -----------                       ----------------
     Credit Suisse First Boston Corporation ..........      $150,000,000
     Salomon Smith Barney, Inc. ......................        90,000,000
     Banc of America Securities LLC ..................        30,000,000
     J.P. Morgan Securities Inc. .....................        30,000,000
                                                            ------------
        Total ........................................      $300,000,000
                                                            ============

                                       S-5

     The underwriting agreement provides that the underwriters are obligated to
purchase all of the notes if any are purchased. The underwriting agreement
provides that if an underwriter defaults, the purchase commitments of
non-defaulting underwriters may be increased or the offering of notes may be
terminated.

     The underwriters propose to offer the notes initially to the public at the
public offering price set forth on the cover page of this prospectus supplement
and to selling group members at that price less a concession of 0.35% of the
principal amount per note. The underwriters and selling group members may allow
a discount of 0.25% of such principal amount per note on sales to other
broker/dealers. After the initial public offering, the underwriters may change
the public offering price and concession and discount to broker/dealers.

     The following table summarizes the compensation and estimated expenses we
will pay:

                                                           Per Note      Total
                                                           --------      -----
Underwriting discounts and commissions payable by us ....     .6%    $1,800,000
Expenses payable by us ..................................    .12%     $  350,000

     The notes are a new issue of securities with no established trading market.
We do not intend to apply for the notes to be listed on any securities exchange
or to be quoted on any quotation system. One or more of the underwriters intends
to make a secondary market for the notes. However, they are not obligated to do
so and may discontinue making a secondary market at any time without notice. No
assurance can be given as to how liquid the trading market for the notes will
be.

     We have agreed to indemnify the underwriters against liabilities under the
Securities Act of 1933, or contribute to payments which the underwriters may be
required to make in respect thereof.

     The underwriters may engage in over-allotment, stabilizing transactions,
syndicate covering transactions and penalty bids in accordance with Regulation M
under the Securities Exchange Act of 1934.

     *    Over-allotment involves syndicate sales in excess of the offering
          size, which creates a syndicate short position.
     *    Stabilizing transactions permit bids to purchase the underlying
          security so long as the stabilizing bids do not exceed a specified
          maximum.
     *    Syndicate covering transactions involve purchases of the notes in the
          open market after the distribution has been completed in order to
          cover syndicate short positions.
     *    Penalty bids permit the underwriters to reclaim a selling concession
          from a syndicate member when the notes originally sold by such
          syndicate member are purchased in a stabilizing transaction or a
          syndicate covering transaction to cover syndicate short positions.
          Such stabilizing transactions, syndicate covering transactions and
          penalty bids may cause the price of the notes to be higher than it
          would otherwise be in the absence of such transactions. These
          transactions, if commenced, may be discontinued at any time.

     The underwriters and their affiliates engage in transactions with us, our
affiliates and our parent or perform services for us, our affiliates and our
parent in the ordinary course of business. Those transactions and services
include investment banking and commercial banking services, and serving as an
agent and/or lender on some of our credit agreements. The underwriters and their
affiliates received customary fees for these transactions and services. In this
regard, banking affiliates of each of Salomon Smith Barney, Inc. and Banc of
America Securities LLC are lenders to us and received a portion of the proceeds
of our short-term borrowings that will be repaid with the proceeds of sale of
the notes, and a banking affiliate of J.P. Morgan Securities Inc. is a lender to
us. In addition, Credit Suisse First Boston Corporation and Banc of America
Securities LLC are dealers under our commercial paper program, and J.P. Morgan
Securities Inc and an affiliate of Salomon Smith Barney, Inc. are remarketing
agents for certain series of pollution control bonds for which we are liable.

                                       S-6

Prospectus


                        ARIZONA PUBLIC SERVICE COMPANY
                                 $525,000,000
                             First Mortgage Bonds
                                Debt Securities


     We may offer and sell first mortgage bonds and debt securities from time to
time in one or more  offerings.  This  prospectus  provides  you with a  general
description of the first mortgage bonds and debt securities we may offer.

     Each time we sell first mortgage bonds or debt securities,  we will provide
a supplement to this prospectus  that contains  specific  information  about the
offering  and the  terms of the first  mortgage  bonds or debt  securities.  The
supplement  may also  add,  update,  or  change  information  contained  in this
prospectus.  You should carefully read this prospectus and any supplement before
you invest in any of our first mortgage bonds or debt securities.

     NEITHER THE  SECURITIES AND EXCHANGE  COMMISSION  NOR ANY STATE  SECURITIES
COMMISSION HAS APPROVED OR  DISAPPROVED  OF THESE  SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

                                   ----------

                The date of this prospectus is January 21, 2000

                               TABLE OF CONTENTS

                                                                      Page
                                                                      ----

    About This Prospectus ...........................................   3
    Forward-Looking Statements ......................................   3
    Where You Can Find More Information .............................   4
    Business of Arizona Public Service Company ......................   5
    Ratio of Earnings to Fixed Charges ..............................   5
    Use of Proceeds .................................................   5
    Description of First Mortgage Bonds .............................   5
    Description of Debt Securities ..................................   9
    Global Securities ...............................................  15
    Regarding the Trustees ..........................................  16
    Plan of Distribution ............................................  17
    Experts .........................................................  17
    Legal Opinions ..................................................  17

                                       2

                             ABOUT THIS PROSPECTUS

     This  prospectus is part of a shelf  registration  statement  that we filed
with the United  States  Securities  and  Exchange  Commission,  or the SEC. You
should rely only on the  information  contained or  incorporated by reference in
this prospectus and in any  supplement.  We have not authorized any other person
to provide you with different information. If anyone provides you with different
or  inconsistent  information,  you  should  not rely on it. We will not make an
offer to sell these  securities in any  jurisdiction  where the offer or sale is
not  permitted.  You  should  assume  that  the  information  appearing  in this
prospectus and the supplement to this  prospectus is accurate as of the dates on
their covers.  Our business,  financial  condition,  results of operations,  and
prospects may have changed since those dates.

                          FORWARD-LOOKING STATEMENTS

     This prospectus, any accompanying prospectus supplement, and the additional
information  described  under the heading "Where You Can Find More  Information"
may  contain  forward-looking  statements  within  the  meaning  of the  Private
Securities  Litigation Reform Act of 1995. These statements are subject to risks
and  uncertainties  and  are  based  on  the  beliefs  and  assumptions  of  our
management,  based on information currently available to our management. When we
use words such as  "believes,"  "expects,"  "anticipates,"  "intends,"  "plans,"
"estimates,"  "should," or similar  expressions,  we are making  forward-looking
statements.

     Forward-looking statements are not guarantees of performance.  They involve
risks, uncertainties,  and assumptions. Our future results may differ materially
from those expressed in these  forward-looking  statements.  Many of the factors
that will determine  these results are beyond our ability to control or predict.
These factors include, but are not limited to, the ongoing  restructuring of the
electric  industry;  the  outcome  of  regulatory  proceedings  relating  to the
restructuring;  regulatory,  tax, and environmental legislation;  our ability to
successfully  compete  outside  our  traditional  regulated  markets;   regional
economic  conditions,  which could affect customer growth;  the cost of debt and
equity capital;  weather  variations  affecting  customer  usage;  technological
developments   in  the  electric   industry;   Year  2000   issues;   and  other
uncertainties,  all of which  are  difficult  to  predict  and many of which are
beyond  our  control.  You  are  cautioned  not to  put  undue  reliance  on any
forward-looking statements. For those statements, we claim the protection of the
safe harbor for forward-looking  statements  contained in the Private Securities
Litigation Reform Act of 1995.

                                       3

                      WHERE YOU CAN FIND MORE INFORMATION


AVAILABLE INFORMATION

     We file annual,  quarterly, and special reports, and other information with
the SEC.  Our SEC filings are  available  to the public over the Internet at the
SEC's web site:  http://www.sec.gov.  You may also read and copy any document we
file at the SEC's public  reference  rooms in  Washington,  D.C.,  New York, New
York, and Chicago,  Illinois. You may call the SEC at 1-800-SEC-0330 for further
information  on the  public  reference  rooms.  Reports  and  other  information
concerning  us can also be  inspected  and copied at the offices of the New York
Stock Exchange at 20 Broad Street, New York, New York 10005. You can also obtain
additional information about us at our web site: http://www.apsc.com.

INCORPORATION BY REFERENCE

     The SEC allows us to incorporate by reference the  information we file with
them, which means that we can disclose important information to you by referring
you to those documents.  The information incorporated by reference is considered
to be part of this prospectus,  and later  information that we file with the SEC
will  automatically  update and supersede  this  information.  We incorporate by
reference the documents listed below and any future filings we make with the SEC
under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934
until all securities are sold under this prospectus.

     *    Annual  Report on Form 10-K for the  fiscal  year ended  December  31,
          1998;
     *    Quarterly Reports on Form 10-Q for the fiscal quarters ended March 31,
          June 30, and September 30, 1999; and
     *    Current  Reports on Form 8-K dated  January 11,  February  18, May 14,
          August 26, September 21, and November 2, 1999.

     You may request a copy of these  filings  and will  receive a copy of these
filings, at no cost, by writing or telephoning us at the following address:

      Arizona Public Service Company
      Office of the Secretary
      Station 8102
      P.O. Box 53999
      Phoenix, Arizona 85072-3999
      (602) 379-2608

                                       4

                  BUSINESS OF ARIZONA PUBLIC SERVICE COMPANY

     We were  incorporated  in 1920  under the laws of Arizona  and are  engaged
principally  in serving  electricity  in the State of Arizona.  We are Arizona's
largest  electric  utility.  We are a  wholly-owned  subsidiary of Pinnacle West
Capital  Corporation.  Our principal  executive offices are located at 400 North
Fifth Street, Phoenix, Arizona 85004, 602-250-1000.

                      RATIO OF EARNINGS TO FIXED CHARGES

     The  following  table sets forth the  historical  ratio of our  earnings to
fixed charges for each of the indicated periods:

      Nine Months
         Ended                        Twelve Months Ended
     -------------    ----------------------------------------------------
     September 30,                       December 31,
     -------------    ----------------------------------------------------
          1999        1998        1997        1996        1995        1994
          ----        ----        ----        ----        ----        ----
          2.02        3.19        3.07        2.84        2.77        2.96

     For the purposes of these computations,  earnings are defined as the sum of
our  pre-tax  income  plus  our  fixed  charges  and the  fixed  charges  of our
subsidiaries.  Fixed charges  consist of interest on debt,  amortization of debt
discount, premium, and expense, and an estimated interest factor in rentals.

                                USE OF PROCEEDS

     We will add the net proceeds from any sale of first  mortgage bonds or debt
securities to our general corporate funds. We will use the net proceeds to repay
debt and for general  corporate  purposes.  A prospectus  supplement may include
other uses of the net proceeds.

                      DESCRIPTION OF FIRST MORTGAGE BONDS

GENERAL

     The  following  description  highlights  the  general  terms  of the  first
mortgage bonds. When we offer first mortgage bonds in the future, the prospectus
supplement will explain the particular  terms of those securities and the extent
to which these general provisions will not apply.

     Our mortgaged  property  will secure the first  mortgage  bonds.  The first
mortgage  bonds will be issued under a Mortgage  and Deed of Trust,  dated as of
July 1, 1946,  between us and The Bank of New York.  The  Mortgage  allows us to
issue first mortgage bonds in one or more series.

     We have summarized  selected  provisions of the Mortgage below. The summary
is not  complete.  We have filed the form of the  Mortgage  as an exhibit to the
registration  statement and you should read any  provisions of the Mortgage that
may be important to you.

     You should refer to the prospectus  supplement  attached to this prospectus
for the following information about a new series of first mortgage bonds:

     *    the aggregate principal amount of the first mortgage bonds;
     *    the date on which the first mortgage bonds mature;
     *    the interest rate;
     *    when the interest on the first mortgage bonds accrues and is payable;
     *    whether and when we can redeem the first mortgage  bonds,  and at what
          price;
     *    the record dates for the payment of interest and principal;
     *    whether the first  mortgage bonds will be issued in the form of one or
          more global securities; and
     *    any other terms.

                                       5

     We will pay interest to the person in whose name the first  mortgage  bonds
are  registered  at the close of business on the record date that  precedes  the
interest payment date. The supplemental  indenture to the Mortgage that contains
the terms of the first mortgage bonds will also contain the record date. We will
issue the first mortgage bonds as fully registered  bonds,  without coupons,  in
$1,000  denominations and multiples  thereof.  The holders of the first mortgage
bonds may transfer them at any time without any service or other charge,  except
for transfer taxes and other governmental  charges, if any. We, the trustee, and
any of our  agents may treat the  registered  holder of a debt  security  as the
absolute owner for the purpose of making payments,  giving notices,  and for all
other purposes.

     Other  than  the  protections  described  in  this  prospectus  and  in the
prospectus supplement, holders of first mortgage bonds would not be protected by
the covenants in the Mortgage from a highly-leveraged transaction.

REDEMPTION

     Unless indicated differently in a prospectus supplement,  we may redeem the
first  mortgage  bonds at their  principal  amount plus accrued  interest to the
redemption date in any of the following ways:

     *    in whole  or in part  using  the  proceeds  when any of our  mortgaged
          property is taken under eminent domain;
     *    in  whole  or in  part  using  the  proceeds  of  the  sale  or  other
          disposition  of  property  that  is  released  from  the  lien  of the
          Mortgage;
     *    in  whole,   together  with  all  other  first   mortgage  bonds  then
          outstanding,  within  twelve  months of a  transaction  involving  the
          transfer of  substantially  all of the property subject to the lien of
          the Mortgage; or
     *    in whole or in part with cash deposited in a replacement fund.

SECURITY

     The  first  mortgage  bonds  will  rank on an equal  basis  with all  first
mortgage  bonds at any time  outstanding  under  the  Mortgage,  except  for any
sinking fund or similar fund that is provided  for in a particular  series.  The
Mortgage creates a first mortgage lien on substantially all the property we own.
However,  the lien  does  not  cover a  combined  cycle  plant  that we lease or
interests in Unit 2 of the Palo Verde Nuclear  Generating Station that we lease,
or any other property specifically excluded from the Mortgage. The Mortgage lien
and the title to some of our  properties  are subject to excepted  encumbrances,
minor leases, defects, irregularities,  and deficiencies, and are subject to the
considerations discussed below regarding the Four Corners Plant and Navajo Plant
locations.  The Mortgage  lien also extends to all property  acquired  after the
effective date of the Mortgage,  other than specifically excluded property,  for
which  proper  filings and  recordings  have been made.  In the case of property
acquired after the effective date of the Mortgage  lien,  however,  the Mortgage
lien is subject to encumbrances  and to liens existing or placed on the property
at the time we acquire it.

     Both the Four  Corners  Plant and the Navajo  Plant are located on property
held under leases from the Navajo Tribe and easements  from the Secretary of the
Interior.  The leases  extend  from their  effective  dates in 1966 and 1969 for
terms of 50 years with  rights of renewal  for up to 25  additional  years.  The
easements are for 50-year terms from the same effective  dates.  Although we own
the rights granted to us by the leases from the Navajo Tribe, we do not make any
representation about the Navajo Tribe's interest in the lands leased, but we are
not aware of any  assertion of a contesting  claim to the lands.  We also do not
make any  representations  about the  enforceability  of the leases  against the
Navajo Tribe.

     The Mortgage requires us to keep our property encumbered in good repair and
working order as an operating system.  However,  we are permitted to permanently
discontinue or reduce the capacity of any property if:

     *    in the  judgment of our Board of  Directors,  it is  desirable  in the
          conduct of our business;
     *    a regulatory authority orders us to do so; or

                                       6

     *    we are going to sell or dispose of the property.

     If we are not in default under the  Mortgage,  we may obtain a release from
the Mortgage lien of:

     *    unserviceable,  obsolete,  or  unnecessary  property,  but  only if we
          replace the property with property of equal value; or
     *    other property that we have sold or otherwise disposed of, but only if
          we:
          *    deposit with the trustee cash in an amount equal to the released
               property's fair value;
          *    use redeemed or retired first mortgage bonds in an amount equal
               to the released property's fair value; or
          *    use as a credit additional property we acquired within the
               preceding five years that has fair value equal to the released
               property's fair value.

     The  trustee  may,  and upon our request  must,  cancel and  discharge  the
Mortgage  lien and all  supplemental  indentures  to the  Mortgage  when we have
repaid all of the debt secured by the Mortgage.

ISSUANCE OF ADDITIONAL FIRST MORTGAGE BONDS

     We may issue  additional  first  mortgage  bonds  under the  Mortgage  in a
principal amount equal to:

     *    60% of net property additions;
     *    the  principal  amount of redeemed or retired  first  mortgage  bonds;
          and/or
     *    deposited cash,

but only if our  adjusted  net  earnings  over the  twelve-month  period  within
fifteen months  preceding the month in which we issue the bonds are at least two
times the annual  interest on all  outstanding  first  mortgage  bonds after the
issuance  and on debt  secured  by prior  liens.  There are  exceptions  to this
earnings  coverage  requirement  for first mortgage bonds issued on the basis of
redeemed or retired  first  mortgage  bonds when the  redeemed or retired  first
mortgage  bonds had a higher  rate of  interest  and when other  conditions  are
satisfied.

     We can support the issuance of new first  mortgage  bonds by using property
located on leaseholds or easements,  such as the Four Corners and Navajo Plants,
if the leasehold or easement has an unexpired term of, or the term is extendable
at our option for, at least 30 years  after the date of  issuance,  or if we may
remove the property without compensation.

     As of September 30, 1999, we estimate that the Mortgage  would have allowed
us to issue up to  approximately  $2.34  billion of  additional  first  mortgage
bonds.  In addition to complying  with the Mortgage  restrictions  placed on the
issuance of additional  first mortgage bonds, we must obtain the approval of the
Arizona Corporation  Commission,  which we refer to as the ACC, before incurring
long-term debt.  Existing ACC orders allow us to have approximately $2.6 billion
in principal  amount of long-term  debt  outstanding  at any one time. We do not
expect these orders to limit our ability to meet our capital requirements.

REPLACEMENT FUND

     So long as any of our first  mortgage bonds are  outstanding,  the Mortgage
requires us to deposit  cash with the trustee  each  calendar  year in an amount
related to net additions to our mortgaged utility plant. However, we may satisfy
all or any part of this  requirement by using redeemed or retired first mortgage
bonds, property additions,  or property  retirements.  For 1998, our replacement
fund requirement was about $138 million.  Any cash that we deposit may, upon our
request,  be applied to the redemption or repurchase of first mortgage bonds. We
may withdraw the cash from the trustee by using  additional  property we acquire
or redeemed or retired first mortgage bonds. If we do not withdraw the cash from
the  trustee  within five years of  deposit,  the  trustee  must use the cash to
redeem outstanding first mortgage bonds. The prospectus supplement relating to a
particular  series of first  mortgage  bonds may  describe  restrictions  on our
ability to redeem the first mortgage bonds with cash we deposit with the trustee
to meet our replacement fund requirements.

                                       7

EVENTS OF DEFAULT

     The following are defaults under the Mortgage:

     *    our failure to pay the  principal of any first  mortgage bond when due
          and payable;
     *    our failure to pay interest on any first  mortgage bond within 60 days
          after it is due and payable;
     *    our failure to pay any  installment of any fund required to be applied
          to the purchase or redemption of first  mortgage  bonds within 60 days
          after it is due and payable;
     *    bankruptcy, insolvency, and reorganization events involving us; and
     *    our  failure to  perform  any other  covenant  of the  Mortgage  which
          continues for 90 days after notice by the trustee or holders of 15% in
          principal amount of eligible bonds.

     The  Mortgage  allows the  trustee to  withhold  notice of  defaults if the
trustee determines in good faith that withholding the notice is in the interests
of the  bondholders.  The trustee may not withhold  notice of any default in the
payment of principal or interest or any sinking,  improvement,  replacement,  or
purchase fund installment.

     Those holding at least a majority in principal amount of the first mortgage
bonds may direct the time,  method,  and place of conducting  any proceeding for
any remedy available to the trustee.  However, the trustee may decline to follow
any direction  under some  circumstances,  including  the  trustee's  good faith
determination that it will not be sufficiently indemnified for any expenditures.
We are  required to file with the  trustee,  on or before July 1 of each year, a
certificate  stating we have complied with all of the provisions of the Mortgage
and that we are not in default and, if we have not  complied,  stating all known
defaults.

MODIFICATION OF THE MORTGAGE

     The Mortgage and the rights of bondholders may be modified if the following
parties consent to the modification:

     *    us;
     *    the trustee, if the trustee is affected by the modification;
     *    holders  of at least 70% in  principal  amount  of the first  mortgage
          bonds, if all series are affected by the modification; or
     *    holders  of at least 70% in  principal  amount of any  series of first
          mortgage  bonds  affected by the  modification,  if all series are not
          affected.

     However,  the holder of each first  mortgage  bond affected must consent to
any modification that would:

     *    affect the rights of the holder to receive  payment of the  principal,
          premium,  or interest on any first  mortgage bonds on the dates due or
          to institute suit to enforce such right;
     *    permit the creation of an  additional  lien ranking  prior or equal to
          the lien of the Mortgage to any of the mortgaged property;
     *    deprive  any  nonassenting  bondholder  of a lien  upon the  mortgaged
          property for the security of the holder's first mortgage bonds; or
     *    reduce  the  percentage  of  bondholders  required  to  consent  to  a
          modification.

RESTRICTIONS ON DIVIDENDS

     The Mortgage  restricts  the payment of dividends on our common stock under
conditions that have not existed in the past and do not currently exist.

                                       8

                        DESCRIPTION OF DEBT SECURITIES

GENERAL

     The  following  description  highlights  the  general  terms  of  the  debt
securities.  When  we  offer  debt  securities  in the  future,  the  prospectus
supplement will explain the particular  terms of those securities and the extent
to which any of these general provisions will not apply.

     The debt securities will be our unsecured obligations.  The debt securities
may be issued in one or more new series under:

     *    an  Indenture,  dated as of January 1, 1995,  between  The Bank of New
          York and us, in the case of subordinated debt securities; or
     *    an  Indenture,  dated  as of  January  15,  1998,  between  The  Chase
          Manhattan Bank and us, in the case of senior debt securities.

     We have summarized selected provisions of the Indentures below. The summary
is not  complete.  We have filed the forms of the  Indentures as exhibits to the
registration statement and you should read any provisions of the Indentures that
may be important to you. Although separate  Indentures are used for subordinated
debt securities and senior debt securities,  the description of the Indenture in
this section applies to both Indentures, unless otherwise noted.

     You should refer to the prospectus  supplement  attached to this prospectus
for the following information about a new series of debt securities:

     *    title of the debt securities;
     *    the aggregate principal amount of the debt securities or the series of
          which they are a part;
     *    the date on which the debt securities mature;
     *    the interest rate;
     *    when the interest on the debt securities accrues and is payable;
     *    the record dates;
     *    places where principal, premium, or interest will be payable;
     *    periods  within  which,  and  prices  at  which  we  can  redeem  debt
          securities at our option;
     *    any  obligation  on our part to redeem  or  purchase  debt  securities
          pursuant to a sinking fund or at the option of the holder;
     *    denominations and multiples at which debt securities will be issued if
          other than $1,000;
     *    any index or formula from which the amount of principal or any premium
          or interest may be determined;
     *    any allowance for alternative currencies and determination of value;
     *    whether  the debt  securities  are  defeasible  under the terms of the
          Indenture;
     *    whether we are issuing the debt securities as global securities;
     *    any  additional  or different  events of default and any change in the
          right of the trustee or the holders to declare  the  principal  amount
          due and payable if there is any default;
     *    any addition to or change in the covenants in the Indenture; and
     *    any other terms.

     We may sell the debt  securities  at a  substantial  discount  below  their
principal amount. The prospectus  supplement may describe special federal income
tax  considerations  that apply to debt  securities  sold at an  original  issue
discount or to debt  securities  that are  denominated  in a currency other than
United States dollars.

                                       9

     Other  than  the  protections  described  in  this  prospectus  and  in the
prospectus supplement,  holders of debt securities would not be protected by the
covenants in the Indenture from a highly-leveraged transaction.

SUBORDINATION

     The Indenture  relating to the  subordinated  debt securities  states that,
unless otherwise provided in a supplemental indenture or a board resolution, the
debt securities will be subordinate to all senior debt. This is true whether the
senior  debt is  outstanding  as of the  date of the  Indenture  or is  incurred
afterwards.  The balance of the  information  under this heading  assumes that a
supplemental  indenture  or a  board  resolution  results  in a  series  of debt
securities being subordinated obligations.

     The Indenture states that we cannot make payments of principal, premium, or
interest on the subordinated debt if:

     *    the principal, premium or interest on senior debt is not paid when due
          and the  applicable  grace  period for the  default  has ended and the
          default has not been cured or waived; or
     *    the  maturity  of any senior  debt has been  accelerated  because of a
          default.

     The Indenture  provides that we must pay all senior debt in full before the
holders of the subordinated debt securities may receive or retain any payment if
our assets are distributed to our creditors upon any of the following:

     *    dissolution;
     *    winding-up;
     *    liquidation;
     *    reorganization, whether voluntary or involuntary;
     *    bankruptcy;
     *    insolvency;
     *    receivership; or
     *    any other proceedings.

     The  Indenture  provides that when all amounts owing on the senior debt are
paid in full, the holders of the subordinated debt securities will be subrogated
to the rights of the holders of senior debt to receive payments or distributions
applicable to senior debt.

     The Indenture defines senior debt as the principal,  premium,  interest and
any other payment due under any of the  following,  whether  outstanding  at the
date of the Indenture or thereafter incurred, created or assumed:

     *    all of our  debt  evidenced  by  notes,  debentures,  bonds,  or other
          securities  we sell for  money,  including  all of our first  mortgage
          bonds;
     *    all debt of others  of the kinds  described  in the  preceding  bullet
          point that we assume or guarantee in any manner; and
     *    all renewals, extensions, or refundings of debt of the kinds described
          in either of the two preceding bullet points.

     However,  the preceding will not be considered  senior debt if the document
creating the debt or the  assumption  or guarantee of the debt states that it is
not  superior  to or that it is on  equal  footing  with the  subordinated  debt
securities.

     The Indenture  does not limit the  aggregate  amount of senior debt that we
may issue. As of September 30, 1999,  outstanding  senior debt was approximately
$1 billion and subordinated debt was  approximately  $75 million.  As of January
31, 2000, we will redeem all of our outstanding subordinated debt.

                                       10

FORM, EXCHANGE, AND TRANSFER

     Each series of debt  securities  will be issuable only in fully  registered
form  and  without  coupons.  In  addition,  unless  otherwise  specified  in  a
prospectus  supplement,  the debt securities will be issued in  denominations of
$1,000 and multiples of $1,000. We, the trustee, and any of our agents may treat
the  registered  holder of a debt security as the absolute owner for the purpose
of making payments, giving notices, and for all other purposes.

     The  holders  of debt  securities  may  exchange  them for any  other  debt
securities of the same series,  in  authorized  denominations,  like tenor,  and
equal principal  amount.  However,  this type of exchange will be subject to the
terms of the Indenture and any limitations that apply to global securities.

     A holder may transfer debt  securities by presenting the endorsed  security
at the office of a security  registrar or at the office of any transfer agent we
designate.  The holder will not be charged for any exchange or  registration  of
transfer,  but we may  require  payment  to cover any tax or other  governmental
charge in connection with the  transaction.  We have appointed the trustee under
each  Indenture as security  registrar.  A prospectus  supplement  will name any
transfer  agent we  designate  for any debt  securities  if  different  from the
security registrar.  We may designate  additional transfer agents or rescind the
designation  of any  transfer  agent or approve a change in the  office  through
which any  transfer  agent  acts at any time,  except  that we will  maintain  a
transfer agent in each place of payment for debt securities.

     If the debt  securities  of any series  and/or  tenor are to be redeemed in
part, we will not be required to do any of the following:

     *    issue,  register the transfer of, or exchange any debt  securities  of
          that series  and/or tenor  beginning 15 days before the day of mailing
          of a notice of  redemption  of any debt  security that may be selected
          for  redemption  and ending at the close of business on the day of the
          mailing; or
     *    register the transfer of or exchange  any debt  security  selected for
          redemption,  except for an unredeemed  portion of a debt security that
          is being redeemed in part.

PAYMENT AND PAYING AGENTS

     Unless otherwise indicated in the applicable prospectus supplement, we will
pay interest on a debt  security on any  interest  payment date to the person in
whose name the debt security is registered.

     Unless otherwise  indicated in the applicable  prospectus  supplement,  the
principal,  premium,  and interest on the debt securities of a particular series
will be  payable  at the  office of the  paying  agents  that we may  designate.
However,  we may pay any interest by check mailed to the address,  as it appears
in the security register, of the person entitled to that interest.  Also, unless
otherwise indicated in the applicable prospectus supplement, the corporate trust
office of the trustee in The City of New York will be our sole paying  agent for
payments with respect to debt securities of each series.  Any other paying agent
that we initially  designate for the debt securities of a particular series will
be named in the applicable prospectus  supplement.  We may at any time designate
additional  paying  agents or rescind  the  designation  of any paying  agent or
approve a change in the office through which any paying agent acts,  except that
we will maintain a paying agent in each place of payment for the debt securities
of a particular series.

     All money that we pay to a paying  agent for the payment of the  principal,
premium, or interest on any debt securities that remains unclaimed at the end of
two years after the principal,  premium,  or interest has become due and payable
will be repaid to us,  and the holder of the debt  security  may look only to us
for payment.

CONSOLIDATION, MERGER, AND SALE OF ASSETS

     Unless otherwise indicated in the applicable prospectus supplement,  we may
not:

     *    consolidate with or merge into any other entity;
     *    convey,  transfer, or lease our properties and assets substantially as
          an entirety to any entity; or

                                       11

     *    permit  any  entity to  consolidate  with or merge  into us or convey,
          transfer,  or lease its  properties  and  assets  substantially  as an
          entirety to us,

     unless the following conditions are met:

          *    the successor entity is a corporation, partnership, trust, or
               other entity organized and validly existing under the laws of any
               domestic jurisdiction and assumes our obligations on the debt
               securities and under the Indenture;
          *    immediately after giving effect to the transaction, no event of
               default, and no event which, after notice or lapse of time or
               both, would become an event of default, shall have occurred and
               be continuing; and
          *    other conditions are met.

     Upon any merger,  consolidation,  or transfer or lease of  properties,  the
successor  person  will  be  substituted  for  us  under  the  Indenture,   and,
thereafter,  except  in  the  case  of a  lease,  we  will  be  relieved  of all
obligations and covenants under the Indenture and the debt securities.

EVENTS OF DEFAULT

     Each of the following  will be an event of default under the Indenture with
respect to debt securities of any series:

     *    our failure to pay principal of or any premium on any debt security of
          that series when due;
     *    our failure to pay any interest on any debt  securities of that series
          when due, and the continuance of that failure for 30 days;
     *    our failure to deposit any sinking fund payment,  when due, in respect
          of any debt securities of that series;
     *    our failure to perform  any of our other  covenants  in the  Indenture
          relating to that  series and the  continuance  of that  failure for 90
          days after written notice has been given by the trustee or the holders
          of at least 25% in principal amount of the outstanding debt securities
          of that series;
     *    bankruptcy, insolvency, or reorganization events involving us; and
     *    any other event of default for that series described in the applicable
          prospectus supplement.

     If an event of  default  occurs  and is  continuing  other than an event of
default  relating  to  bankruptcy,  insolvency,  or  reorganization,  either the
trustee or the  holders  of at least 25% in  aggregate  principal  amount of the
outstanding  debt  securities  of the affected  series may declare the principal
amount of the debt securities of that series to be due and payable  immediately.
In the case of any debt security that is an original issue discount  security or
the  principal  amount of which is not then  determinable,  the  trustee  or the
holders of at least 25% in aggregate  principal  amount of the outstanding  debt
securities of that series may declare the portion of the principal amount of the
debt security specified in the terms of such debt security to be immediately due
and payable upon an event of default.

     If an event of default involving bankruptcy,  insolvency, or reorganization
occurs,  the principal  amount of all the debt securities of the affected series
will automatically,  and without any action by the trustee or any holder, become
immediately due and payable.  After any  acceleration,  but before a judgment or
decree based on acceleration,  the holders of a majority in aggregate  principal
amount of the  outstanding  debt securities of that series may rescind and annul
the  acceleration  if all  events of  default,  other  than the  non-payment  of
accelerated principal, have been cured or waived as provided in the Indenture.

     The trustee  will be under no  obligation  to exercise any of its rights or
powers  under the  Indenture  at the request or direction of any of the holders,
unless the holders have  offered the trustee  reasonable  indemnity.  Subject to
provisions for the indemnification of the trustee,  the holders of a majority in
principal  amount of the outstanding debt securities of any series will have the
right to direct the time, method, and place of conducting any proceeding for any
remedy  available to the trustee,  or exercising any trust or power conferred on
the trustee, with respect to the debt securities of that series.

                                       12

     No holder of a debt security of any series will have any right to institute
any proceeding  under the Indenture,  or for the  appointment of a receiver or a
trustee, or for any other remedy under the Indenture, unless:

     *    the  holder  has  previously  given the  trustee  written  notice of a
          continuing  event of default  with respect to the debt  securities  of
          that series;
     *    the  holders  of at least  25% in  aggregate  principal  amount of the
          outstanding  debt securities of that series have made written request,
          and the holder or holders have offered  reasonable  indemnity,  to the
          trustee to institute the proceeding as trustee; and
     *    the  trustee  has  failed to  institute  the  proceeding,  and has not
          received from the holders of a majority in aggregate  principal amount
          of  the  outstanding  debt  securities  of  that  series  a  direction
          inconsistent  with  the  request  within  60 days  after  the  notice,
          request, and offer.

     The  limitations  provided  above do not  apply to a suit  instituted  by a
holder of a debt  security  for the  enforcement  of payment  of the  principal,
premium, or interest on the debt security on or after the applicable due date.

     We are required to furnish to the trustee annually a certificate of various
officers  stating  whether  or  not  we are in  default  in the  performance  or
observance of any of the terms, provisions, and conditions of the Indenture and,
if so, specifying all known defaults.

MODIFICATION AND WAIVER

     In limited  cases the trustee,  as well as us, may make  modifications  and
amendments to the Indenture  without the consent of the holders of any series of
debt  securities.  The  trustee may make  modifications  and  amendments  to the
Indenture with the consent of  the holders of not less than 66 2/3% in aggregate
principal  amount of the outstanding  debt securities of each series affected by
the  modification  or amendment.  However,  without the consent of the holder of
each outstanding debt security affected, no modification or amendment may:

     *    change the stated  maturity of the principal of, or any installment of
          principal of or interest on, any debt security;
     *    reduce the  principal  amount of, or any premium or  interest  on, any
          debt security;
     *    reduce the amount of principal of an original issue discount  security
          or any other debt security  payable upon  acceleration of the maturity
          of the security;
     *    change  the place or  currency  of  payment  of  principal  of, or any
          premium or interest on, any debt security;
     *    impair the right to institute suit for the  enforcement of any payment
          on or with respect to any debt security; or
     *    reduce  the  percentage  in  principal   amount  of  outstanding  debt
          securities of any series, the consent of whose holders is required for
          modification  or amendment of the  Indenture  necessary  for waiver of
          compliance  with  certain  provisions  of the  Indenture or of certain
          defaults,  or modify  the  provisions  of the  Indenture  relating  to
          modification and waiver.

     Compliance  with certain  restrictive  provisions  of the  Indenture may be
waived by the holders of not less than 66 2/3% in aggregate  principal amount of
the  outstanding  debt  securities  of any series.  The holders of a majority in
principal  amount of the outstanding debt securities of any series may waive any
past default under the Indenture, except:

     *    a default in the payment of principal, premium, or interest; and
     *    a default under covenants and provisions of the Indenture which cannot
          be amended without the consent of the holder of each  outstanding debt
          security of the affected series.

                                       13

     In determining whether the holders of the requisite principal amount of the
outstanding debt securities have given or taken any direction,  notice, consent,
waiver, or other action under the Indenture as of any date:

     *    the  principal  amount  of  an  outstanding  original  issue  discount
          security  will be the  amount of the  principal  that would be due and
          payable upon acceleration of the maturity on that date,
     *    if the  principal  amount  payable  at the stated  maturity  of a debt
          security is not determinable,  the principal amount of the outstanding
          debt  security will be an amount  determined in the manner  prescribed
          for the debt security; and
     *    the principal  amount of an outstanding  debt security  denominated in
          one or more foreign  currencies will be the U.S. dollar  equivalent of
          the  principal  amount of the debt  security or, in the case of a debt
          security  described in the previous clause above, the amount described
          in that clause.

     If debt  securities  have been fully defeased or if we have deposited money
with the  trustee  to  redeem  debt  securities,  they  will  not be  considered
outstanding.

     Except in limited  circumstances,  we will be  entitled to set any day as a
record  date for the purpose of  determining  the  holders of  outstanding  debt
securities  of any  series  entitled  to  give or take  any  direction,  notice,
consent,  waiver, or other action under the Indenture. In limited circumstances,
the trustee  will be  entitled to set a record date for action by holders.  If a
record date is set for any action to be taken by holders of a particular series,
the  action may be taken only by persons  who are  holders of  outstanding  debt
securities of that series on the record date.  To be effective,  the action must
be taken by holders of the  requisite  principal  amount of the debt  securities
within a specified period  following the record date. For any particular  record
date,  this  period  will be 180  days or any  other  shorter  period  as we may
specify. The period may be shortened or lengthened, but not beyond 180 days.

DEFEASANCE AND COVENANT DEFEASANCE

     We may elect to have the provisions of the Indenture relating to defeasance
and discharge of  indebtedness,  or defeasance of  restrictive  covenants in the
Indenture,  applied to the debt  securities  of any series,  or to any specified
part  of a  series.  The  prospectus  supplement  describing  a  series  of debt
securities will state whether we can make these elections for that series.

     DEFEASANCE AND DISCHARGE

     We will be discharged from all of our obligations  with respect to the debt
securities  of a series  if we  deposit  with  the  trustee  money in an  amount
sufficient to pay the principal, premium, and interest on the debt securities of
that series when due in accordance  with the terms of the Indenture and the debt
securities.  We can also  deposit  securities  that will  provide the  necessary
monies.  However,  we will not be discharged from the obligations to exchange or
register the transfer of debt securities,  to replace stolen, lost, or mutilated
debt securities,  to maintain paying agencies, and to hold moneys for payment in
trust.  The  defeasance or discharge may occur only if we deliver to the trustee
an opinion of counsel  stating  that we have  received  from,  or there has been
published by, the United States Internal Revenue Service a ruling,  or there has
been a change in tax law, in either case to the effect that holders of such debt
securities:

     *    will not recognize  gain or loss for federal  income tax purposes as a
          result of the deposit, defeasance, and discharge; and
     *    will be subject to federal income tax on the same amount,  in the same
          manner,  and at the  same  times as  would  have  been the case if the
          deposit, defeasance, and discharge were not to occur.

     DEFEASANCE OF COVENANTS

     We may elect to omit compliance with restrictive covenants in the Indenture
and any additional covenants that may be described in the applicable  prospectus
supplement  for a series of debt  securities.  This  election will preclude some
actions from being  considered  defaults  under the Indenture for the applicable
series.  In order to exercise  this option,  we will be required to deposit,  in
trust for the  benefit  of the  holders of debt  securities,  funds in an amount
sufficient to pay the principal, premium and interest

                                       14

on the debt securities of the applicable  series. We may also deposit securities
that will provide the necessary  monies.  We will also be required to deliver to
the  trustee  an opinion  of  counsel  to the  effect  that  holders of the debt
securities  will not recognize gain or loss for federal income tax purposes as a
result of such deposit and defeasance of certain obligations and will be subject
to federal  income tax on the same  amount,  in the same  manner and at the same
times as would  have been the case if the  deposit  and  defeasance  were not to
occur.  If we exercise this option with respect to any debt  securities  and the
debt  securities  are declared due and payable  because of the occurrence of any
event of default,  the amount of funds deposited in trust would be sufficient to
pay amounts due on the debt  securities at the time of their  respective  stated
maturities  but may not be sufficient to pay amounts due on the debt  securities
on any acceleration  resulting from an event of default.  In that case, we would
remain liable for the additional payments.

GOVERNING LAW

     The  law  of  the  State of New York will govern the Indenture and the debt
securities.

                               GLOBAL SECURITIES

     Some or all of the first  mortgage  bonds or debt  securities of any series
may be represented, in whole or in part, by one or more global securities, which
will have an  aggregate  principal  amount  equal to that of the first  mortgage
bonds or debt securities  they represent.  We will register each global security
in the name of a depositary or nominee identified in a prospectus supplement and
deposit the global security with the depositary or nominee. Each global security
will bear a legend  regarding the  restrictions on exchanges and registration of
transfer  referred  to below  and  other  matters  specified  in a  supplemental
indenture to the Mortgage or the Indenture.

     No  global  security  may be  exchanged  for first  mortgage  bonds or debt
securities  registered,  and no transfer of a global security may be registered,
in the name of any person other than the depositary  for the global  security or
any nominee of the depositary, unless:

     *    the  depositary  has  notified  us that it is  unwilling  or unable to
          continue  as  depositary  for the global  security or has ceased to be
          qualified to act as depositary;
     *    a default has  occurred  and is  continuing  with respect to the first
          mortgage bonds or debt securities  represented by the global security;
          or
     *    any other  circumstances exist that may be described in the applicable
          supplemental indenture and prospectus supplement.

     We will register all securities issued in exchange for a global security or
any portion of a global security in the names specified by the depositary.

     As long as the  depositary  or its  nominee is the  registered  holder of a
global security, the depositary or nominee will be considered the sole owner and
holder of the global  security and the first mortgage  bonds or debt  securities
that it  represents.  Except in the  limited  circumstances  referred  to above,
owners of beneficial interests in a global security will not:

     *    be entitled to have the global  security  or first  mortgage  bonds or
          debt securities registered in their names;
     *    receive or be entitled to receive  physical  delivery of  certificated
          first  mortgage  bonds or debt  securities  in  exchange  for a global
          security; and
     *    be  considered  to be the owners or holders of the global  security or
          any first mortgage bonds or debt  securities for any purpose under the
          Mortgage or the Indenture.

     We will make all payments of principal,  premium,  and interest on a global
security  to the  depositary  or its  nominee.  The  laws of some  jurisdictions
require that  purchasers of securities  take physical  delivery of securities in
definitive form. These laws make it difficult to transfer  beneficial  interests
in a global security.

                                       15

     Ownership of beneficial  interests in a global  security will be limited to
institutions that have accounts with the depositary or its nominee,  referred to
as  Participants,  and to persons  that may hold  beneficial  interests  through
Participants.  In  connection  with the  issuance  of any global  security,  the
depositary will credit, on its book-entry  registration and transfer system, the
respective  principal  amounts  of  first  mortgage  bonds  or  debt  securities
represented  by the  global  security  to  the  accounts  of  its  Participants.
Ownership of  beneficial  interests in a global  security  will only be shown on
records maintained by the depositary or the Participant.  Likewise, the transfer
of ownership interests will be effected only through the same records. Payments,
transfers,  exchanges,  and other matters relating to beneficial  interests in a
global security may be subject to various policies and procedures adopted by the
depositary  from time to time.  Neither we, the  trustee,  nor any of our agents
will have  responsibility or liability for any aspect of the depositary's or any
Participant's  records  relating  to,  or  for  payments  made  on  account  of,
beneficial interests in a global security, or for maintaining,  supervising,  or
reviewing any records relating to the beneficial interests.

                            REGARDING THE TRUSTEES

     The Bank of New York is the trustee  under the Mortgage  and trustee  under
the Indenture  relating to the subordinated debt securities.  We maintain normal
banking arrangements with The Bank of New York, which include:

     *    a commitment in the aggregate  principal amount of approximately $15.8
          million by The Bank of New York pursuant to a reimbursement  agreement
          related to a letter of credit issued on our behalf in connection  with
          an issuance of  pollution  control  bonds,  the proceeds of which were
          made available to us; and
     *    a $26.6  million  commitment  by The  Bank of New York  pursuant  to a
          revolving credit  agreement,  approximately  $6.3 million of which was
          outstanding at September 30, 1999.

     The Bank of New York also serves as:

     *    trustee for the holders of several  issues of pollution  control bonds
          issued on our behalf;
     *    trustee under our senior note indenture;
     *    investment manager for our nonunion post-retirement medical fund; and
     *    custodian of international fixed-income assets for our pension plan.

     An affiliate of The Bank of New York is the remarketing  agent for a series
of our pollution control bonds.

     The Chase Manhattan Bank is the trustee under the Indenture relating to the
senior debt securities.  We maintain normal banking  arrangements with The Chase
Manhattan Bank. The Chase Manhattan Bank also:

     *    serves as trustee for the holders of several series of bonds issued by
          a party  unaffiliated  with us,  secured by, among other  things,  our
          payments under our Palo Verde Nuclear Generating Station leases;
     *    serves as an issuing and paying agent with  respect to our  commercial
          paper program; and
     *    has a  commitment  to lend us up to $49.4  million  under a  revolving
          credit agreement, approximately $13.8 million of which was outstanding
          as of September 30, 1999.

     In  addition,  an  affiliate  of The  Chase  Manhattan  Bank  is the  owner
participant  under a trust to which we sold and leased  back a portion of Unit 2
of the Palo Verde Nuclear Generating Station.

                                       16

                             PLAN OF DISTRIBUTION

     We intend to sell up to $525,000,000 in aggregate  principal  amount of the
offered securities to or through  underwriters or dealers, and may also sell the
offered securities  directly to other purchasers or through agents, as described
in the  prospectus  supplement  relating to an issue of first  mortgage bonds or
debt securities.

     We may distribute the offered  securities  from time to time in one or more
transactions  at a fixed  price or prices,  which may be  changed,  or at market
prices  prevailing at the time of sale, at prices  related to prevailing  market
prices, or at negotiated prices.

     In connection  with the sale of the offered  securities,  underwriters  may
receive  compensation from us or from purchasers of offered  securities for whom
they  act as  agents  in the form of  discounts,  concessions,  or  commissions.
Underwriters may sell offered securities to or through dealers,  and the dealers
may receive compensation in the form of discounts,  concessions,  or commissions
from the underwriters  and/or  commissions from the purchasers for whom they act
as  agents.   Underwriters,   dealers,   and  agents,  who  participate  in  the
distribution of offered  securities,  may be considered to be underwriters,  and
any  discounts  or  commissions  received  by them from us and any profit on the
resale  of  offered  securities  by them may be  considered  to be  underwriting
discounts and commissions under the Securities Act of 1933. We will identify any
person  considered to be an underwriter,  and we will describe any  compensation
received from us in the prospectus supplement.

     We may agree to indemnify underwriters, dealers, and agents who participate
in the distribution of the offered  securities  against  liabilities,  including
liabilities under the Securities Act of 1933.

                                    EXPERTS

     The financial statements  incorporated in this prospectus by reference from
APS' 1998 Annual Report on Form 10-K have been audited by Deloitte & Touche LLP,
independent  auditors as stated in their report, which is incorporated herein by
reference,  and have been so  incorporated  in reliance  upon the report of such
firm given upon their authority as experts in accounting and auditing.

                                LEGAL OPINIONS

     Snell & Wilmer  L.L.P.,  One Arizona  Center,  Phoenix,  Arizona 85004 will
opine on the validity of the offered  securities.  We currently  anticipate that
Sullivan and Cromwell,  1888 Century Park East,  Los Angeles,  California  90067
will opine on the validity of the offered  securities  for any  underwriters  of
securities.  In giving  their  opinions,  Sullivan & Cromwell and Snell & Wilmer
L.L.P.  may rely as to matters  of New Mexico law upon the  opinion of Keleher &
McLeod,  P.A.,  Albuquerque  Plaza, 201 Third NW, 12th Floor,  Albuquerque,  New
Mexico 87102.  Snell & Wilmer L.L.P.  may rely as to all matters of New York law
upon the opinion of Sullivan & Cromwell.  Sullivan & Cromwell may rely as to all
matters of Arizona law upon the opinion of Snell & Wilmer L.L.P.

                                       17



                                      APS
                             Arizona Public Service
                                    Company