Exhibit 4.2


                           MISSISSIPPI POWER COMPANY

                                       TO

                             BANKERS TRUST COMPANY,

                                    TRUSTEE.

                          THIRD SUPPLEMENTAL INDENTURE

                           DATED AS OF MARCH 28, 2000

                                  $100,000,000

                       SERIES C FLOATING RATE SENIOR NOTES

                               DUE MARCH 28, 2002










                               TABLE OF CONTENTS  1


                                                                           PAGE

ARTICLE 1....................................................................2


SECTION 101. Establishment...................................................2
             -------------

SECTION 102. Definitions.....................................................2
             -----------

SECTION 103. Payment of Principal and Interest...............................3
             ---------------------------------

SECTION 104. Determination of Interest.......................................4
             -------------------------

SECTION 105. Denominations...................................................5
             -------------

SECTION 106. Global Securities...............................................5
             -----------------


SECTION 107. Transfer................ .......................................5
             --------


SECTION 108. Redemption......................................................6
             ----------

ARTICLE 2....................................................................6

SECTION 201. Recitals by Company.............................................6
             -------------------

SECTION 202. Ratification and Incorporation of Original Indenture............6
             ----------------------------------------------------

SECTION 203. Executed in Counterparts........................................6
             ------------------------


1This Table of Contents does not constitute part of the Indenture or have
any bearing upon the interpretation of any of its terms and provisions.



                  THIS  THIRD SUPPLEMENTAL INDENTURE is made as of the 28th day
of  March, 2000,  by and between MISSISSIPPI POWER COMPANY,  a Mississippi
corporation, 2992 West Beach, Gulfport, Mississippi 39501 (the "Company"), and
BANKERS TRUST COMPANY, a banking corporation duly organized and existing under
the laws of the State of New York, having its principal corporate trust office
at Four Albany Street, New York, New York 10006 (the "Trustee").

                              W I T N E S S E T H:

                  WHEREAS, the Company has heretofore entered into a Senior Note
Indenture, dated as of May 1, 1998 (the "Original Indenture"),  with Bankers
Trust Company, as supplemented by a First Supplemental Indenture, dated as of
May 19, 1998 (the "First Supplemental Indenture"), with Bankers Trust Company
and by a Second Supplemental Indenture, dated as of May 20, 1998 (the "Second
Supplemental Indenture"), with Bankers Trust Company;

                  WHEREAS,  the Original Indenture is incorporated herein
by this reference and the Original Indenture, as supplemented by the First
Supplemental Indenture,  the Second Supplemental Indenture and this Third
Supplemental Indenture, is herein called the "Indenture";

                  WHEREAS,  under the Original Indenture,  a new series of
Senior Notes may at any time be established by the Board of Directors of the
Company in accordance with the provisions of the Original Indenture and the
terms of such series may be described by a supplemental indenture executed by
the Company and the Trustee;

                  WHEREAS,  the Company proposes to create under the Indenture
a new series of Senior Notes;

                  WHEREAS,  additional Senior Notes of other series hereafter
established, except as may be limited in the Original Indenture as at the time
supplemented and modified,  may be issued from time to time pursuant to the
Indenture as at the time supplemented and modified; and

                  WHEREAS,  all conditions  necessary to authorize the execution
and  delivery of this Third  Supplemental  Indenture  and to make it a valid and
binding obligation of the Company have been done or performed.

                  NOW,   THEREFORE,  in  consideration  of  the  agreements  and
obligations set forth herein and for other good and valuable consideration,  the
sufficiency of which is hereby acknowledged,  the parties hereto hereby agree as
follows:




                                    ARTICLE 1

                              Series C Senior Notes

         SECTION 101. Establishment. There is hereby established a new series of
Senior Notes to be issued under the Indenture, to be designated as the Company's
Series C Floating Rate Senior Notes due March 28, 2002 (the "Series C Notes").

         There are to be authenticated and delivered $100,000,000 principal
amount of Series C Notes,  and no further Series C Notes shall be authenticated
and delivered except as provided by Sections 203, 303, 304, 907 or 1107 of the
Original Indenture.  The Series C Notes shall be issued in definitive fully
registered form.

         The Series C Notes shall be issued in the form of one Global Security
in  substantially the form set out in Exhibit A hereto.  The Depositary with
respect to the Series C Notes shall be The Depository Trust Company.

         The form of the Trustee's Certificate of Authentication for the Series
C Notes shall be in substantially the form set forth in Exhibit B hereto.

         Each Series C Note shall be dated the date of authentication thereof
and shall bear interest from the date of original issuance thereof or from the
most recent Interest Payment Date to which interest has been paid or duly
provided for.

         SECTION  102.  Definitions.  The following defined terms used herein
shall, unless the context otherwise requires, have the meanings specified below.
Capitalized terms used herein for which no definition is provided herein shall
have the meanings set forth in the Original Indenture.

         "Calculation  Agent" means Bankers Trust Company, or its successor
appointed by the Company, acting as calculation agent.

         "Interest etermination  Date" means the second London Business Day
immediately preceding the first day of the relevant Interest Period.

         "Interest Payment Dates" means the 28th day of each month, commencing
April 28, 2000;  provided, however, in the event that any Interest Payment Date
would otherwise be a day that is not a Business Day, the Interest Payment Date
will be the next succeeding Business Day.

         "Interest Period" means the period commencing on an Interest Payment
Date (or, with respect to the initial Interest Period only,  commencing on the
Original Issue Date) and ending on the day before the next succeeding  Interest
Payment Date.

         "LIBOR" for any Interest  Determination  Date will be the Reported Rate
for deposits in U. S. dollars having an index maturity of one month for a period
commencing on the second London Business Day immediately  following the Interest
Determination  Date in amounts  of not less than  $1,000,000,  at  approximately
11:00 a.m., London time, on the Interest Determination Date.

                                       2



         "London Business Day"  means a day that is a Business Day and a day on
which dealings in deposits in U. S. dollars are transacted, or with respect to
any future date are expected to be transacted, in the London interbank market.

         "Original Issue Date" means March 28, 2000.

         "Rate Quotation" is defined in Section 104 hereof.

         "Regular  Record Date" means,  with  respect to each  Interest  Payment
Date,  the close of business on the 15th  calendar day  preceding  such Interest
Payment Date.

         "Reported  Rate" means the rate that appears on Telerate Page 3750 or a
successor  reporter  of  such  rates  selected  by  the  Calculation  Agent  and
acceptable to the Company.

         "Representative Amounts" is defined in Section 104 hereof.

         "Stated Maturity" means March 28, 2002.

         "Telerate  Page 3750" means the display designated on page 3750 on
Bridge Telerate,  Inc. (or such other page as may replace the 3750 page on that
service or such other service as may be nominated by the British Bankers'
Association for the purpose of displaying London interbank offered rates for U.
S. dollar deposits).

         SECTION 103.  Payment of Principal and  Interest.  The principal of the
Series C Notes shall be due at Stated Maturity.  The unpaid principal amount of
the Series C Notes shall bear interest at the rates set  monthly  pursuant to
Section  104 hereof until paid or duly  provided for.  Interest shall be paid
monthly in arrears on each Interest Payment Date to the Person in whose name the
Series C Notes are registered on the Regular Record Date for such Interest
Payment Date, provided that interest payable at the Stated Maturity of principal
or on a Redemption  Date as provided  herein will be paid to the Person to whom
principal is payable.  Any such interest that is not so punctually paid or duly
provided for will forthwith  cease to be payable to the Holders on such Regular
Record  Date and may either be paid to the Person or Persons in whose name the
Series C Notes are 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 C Notes not less than ten (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,
if any, on which the Series C Notes shall be listed, and upon such notice as may
be required by any such  exchange,  all as more fully  provided in the Original
Indenture.

         Payments  of  interest  on the  Series C Notes  will  include  interest
accrued  to but  excluding  the  respective  Interest  Payment  Dates.  Interest
payments  for the Series C Notes shall be computed  and paid on the basis of the
actual number of days elapsed over a 360-day year.

                                       3



         Payment of the  principal  and interest  due at the Stated  Maturity or
earlier  redemption  of the Series C Notes shall be made upon  surrender  of the
Series C Notes at the  Corporate  Trust Office of the Trustee.  The principal of
and interest on the Series C Notes shall be paid 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.  Payments of interest  (including  interest on any
Interest Payment Date) will be made, subject to such surrender where applicable,
at the option of the  Company,  (i) by check mailed to the address of the Person
entitled  thereto as such address shall appear in the Security  Register or (ii)
by wire transfer at such place and to such account at a banking  institution  in
the  United  States as may be  designated  in  writing  to the  Trustee at least
sixteen (16) days prior to the date for payment by the Person entitled thereto.

         SECTION 104.  Determination  of Interest  Rate. The Series C Notes will
bear  interest for each  Interest  Period at a per annum rate  determined by the
Calculation Agent, subject to the maximum interest rate permitted by New York or
other  applicable state law, as such law may be modified by United States law of
general  application.  The interest rate applicable  during each Interest Period
will be  equal to LIBOR on the  Interest  Determination  Date for such  Interest
Period plus 0.08%;  provided,  however, that in certain circumstances  described
below, the interest rate will be determined without reference to LIBOR. Promptly
upon such  determination,  the Calculation Agent will notify the Company and the
Trustee,  if the Trustee is not then serving as the  Calculation  Agent,  of the
interest rate for the new Interest  Period.  The interest rate determined by the
Calculation  Agent,  absent manifest error, shall be binding and conclusive upon
the  beneficial  owners and  Holders of the Series C Notes,  the Company and the
Trustee.

         If the  following circumstances exist on any Interest Determination
Date, the  Calculation  Agent shall determine the interest rate for the Series
C Notes as follows:

                  (1) In the event no Reported Rate appears on Telerate Page
         3750 as of approximately  11:00  a.m.,  London  time,  on an Interest
         Determination Date, the Calculation Agent shall request the principal
         London  offices of each of four major banks in the  London interbank
         market selected by the Calculation Agent (after consultation with the
         Company) to provide a quotation of the rate (the "Rate  Quotation")  at
         which one month deposits in amounts of not less than  $1,000,000 are
         offered by it to prime  banks in the  London interbank  market,  as of
         approximately  11:00 a.m., London time, on such Interest  Determination
         Date, that is representative of single transactions at such time (the
         "Representative Amounts").  If  at  least  two  Rate Quotations are
         provided,  the interest rate will be the arithmetic mean of the Rate
         Quotations obtained by the Calculation Agent, plus 0.08%.

                  (2) In the event no Reported Rate appears on Telerate Page
         3750 as of  approximately  11:00  a.m.,  London  time, on an Interest
         Determination Date and there are fewer than two Rate Quotations, the
         interest rate will be the arithmetic mean of the rates quoted at
         approximately 11:00 a.m.,  New York City time, on such Interest
         Determination Date, by three major banks in New York City selected by
         the Calculation Agent (after consultation with the Company), for loans
         in  Representative Amounts in U. S. dollars to leading European banks,

                                       4



         having an index maturity of one month for a period commencing on the
         second London Business Day immediately following such nterest
         Determination Date, plus 0.08%;  provided,  however, that if fewer than
         three banks selected by the Calculation Agent are quoting such rates,
         the interest rate for the applicable Interest Period will be the same
         as the interest rate in effect for the immediately preceding Interest
         Period.

         Upon the  request  of a Holder of the Series C Notes,  the  Calculation
Agent will  provide to such  Holder the  interest  rate in effect on the date of
such request and, if determined, the interest rate for the next Interest Period.

         SECTION  105.  Denominations.  The Series C Notes may be issued in the
denominations of $1,000, or any integral multiple thereof.

         SECTION 106.  Global  Securities.  The Series C Notes will be issued in
the  form  of one or  more  Global  Securities  registered  in the  name  of the
Depositary (which shall be The Depository Trust Company) or its nominee.  Except
under the limited  circumstances  described below, Series C Notes represented by
the Global  Security  will not be  exchangeable  for, and will not  otherwise be
issuable as, Series C Notes in definitive form. The Global Securities  described
above may not be  transferred  except  by the  Depositary  to a  nominee  of the
Depositary  or by a nominee  of the  Depositary  to the  Depositary  or  another
nominee of the Depositary or to a successor Depositary or its nominee.

         Owners of  beneficial  interests in such a Global  Security will not be
considered  the  Holders  thereof for any purpose  under the  Indenture,  and no
Global Security  representing a Series C Note shall be exchangeable,  except for
another Global Security of like  denomination  and tenor to be registered in the
name of the  Depositary  or its  nominee  or to a  successor  Depositary  or its
nominee.  The rights of Holders of such Global  Security shall be exercised only
through the Depositary.

         A Global Security shall be exchangeable  for Series C Notes  registered
in the names of persons other than the Depositary or its nominee only if (i) the
Depositary  notifies the Company that it is unwilling or unable to continue as a
Depositary for such Global Security and no successor  Depositary shall have been
appointed  by the  Company,  or if at any time  the  Depositary  ceases  to be a
clearing  agency  registered  under  the  Securities  Exchange  Act of 1934,  as
amended, at a time when the Depositary is required to be so registered to act as
such  Depositary  and no successor  Depositary  shall have been appointed by the
Company,  in each case within 90 days after the Company  receives such notice or
becomes  aware of such  cessation,  (ii)  the  Company  in its  sole  discretion
determines  that such Global Security shall be so  exchangeable,  or (iii) there
shall have occurred an Event of Default with respect to the Series C Notes.  Any
Global Security that is exchangeable pursuant to the preceding sentence shall be
exchangeable for Series C Notes registered in such names as the Depositary shall
direct.

         SECTION 107 Transfer.  No service  charge will be made for any transfer
or exchange of Series C Notes,  but payment will be required of a sum sufficient
to cover any tax or other governmental  charge that may be imposed in connection
therewith.

                                       5




         The Company  shall not be required  (a) to issue,  transfer or exchange
any Series C Notes during a period  beginning at the opening of business fifteen
(15) days  before  the day of the  mailing  of a notice  identifying  the serial
numbers  of the Series C Notes to be called  for  redemption,  and ending at the
close of business on the day of the mailing,  or (b) to transfer or exchange any
Series C Notes  theretofore  selected for redemption in whole or in part, except
the unredeemed portion of any Series C Note redeemed in part.

         SECTION  108.  Redemption.  The  Series  C Notes  shall be  subject  to
redemption at the option of the Company, in whole or in part, without premium or
penalty,  on any  Interest  Payment  Date  on or  after  March  28,  2001,  at a
Redemption  Price  equal to 100% of the  principal  amount to be  redeemed  plus
accrued but unpaid interest to the Redemption Date.

         In the event of  redemption  of the Series C Notes in part only,  a new
Series C Note or Notes for the unredeemed  portion will be issued in the name or
names of the Holders thereof upon the surrender thereof.

         The Series C Notes will not have a sinking fund.

         Notice of redemption  shall be given as provided in Section 1104 of the
Original Indenture.

         Any  redemption  of less  than all of the  Series C Notes  shall,  with
respect to the principal thereof, be divisible by $1,000.

                                    ARTICLE 2

                            Miscellaneous Provisions

         SECTION  201.   Recitals  by  Company.   The  recitals  in  this  Third
Supplemental  Indenture are made by the Company only and not by the Trustee, and
all of the  provisions  contained  in the  Original  Indenture in respect of the
rights,  privileges,  immunities,  powers  and  duties of the  Trustee  shall be
applicable in respect of Series C Notes and of this Third Supplemental Indenture
as fully and with like effect as if set forth herein in full.

         SECTION 202.  Ratification and Incorporation of Original Indenture.  As
heretofore  supplemented  by the First  Supplemental  Indenture  and the  Second
Supplemental  Indenture and as supplemented hereby, the Original Indenture is in
all respects  ratified and  confirmed,  and the  Original  Indenture,  the First
Supplemental  Indenture,  the  Second  Supplemental  Indenture  and  this  Third
Supplemental  Indenture  shall be read,  taken and construed as one and the same
instrument.

         SECTION  203.  Executed  in  Counterparts.   This  Third   Supplemental
Indenture may be simultaneously executed in several counterparts,  each of which
shall  be  deemed  to be an  original,  and  such  counterparts  shall  together
constitute but one and the same instrument.


                                      6





0540138.doc

                  IN  WITNESS  WHEREOF,   each  party  hereto  has  caused  this
instrument to be signed in its name and behalf by its duly authorized  officers,
all as of the day and year first above written.

ATTEST:                            MISSISSIPPI POWER COMPANY


By:                                By:
   -----------------------
     Vicki L. Pierce                 Michael W. Southern
     Assistant Secretary             Vice President, Secretary, Treasurer and
                                     Chief Financial Officer



ATTEST:                                     BANKERS TRUST COMPANY, as Trustee


By:                                                  By:
   -----------------------------------------
Name:                                                Name:
Title:                                               Title:







                                    EXHIBIT A

                              FORM OF SERIES C NOTE






NO. __                                                  CUSIP NO. 605417BL7


                            MISSISSIPPI POWER COMPANY
                       SERIES C FLOATING RATE SENIOR NOTE
                               DUE MARCH 28, 2002



       Principal Amount:                  $_____________

       Regular Record Date:               15th calendar day prior to Interest
                                          Payment Date

       Original Issue Date:               March 28, 2000

       Stated Maturity:                   March 28, 2002

       Interest Payment Dates:            28th day of each month;  provided,
                                          however,  in the event that any
                                          Interest Payment Date would otherwise
                                          be a day that is not a Business Day,
                                          the Interest Payment Date will be the
                                          next succeeding Business Day

       Interest Rate:                     LIBOR plus 0.08% per annum, as set on
                                          each Interest Determination Date

       Interest Determination Dates:      2nd London Business Day immediately
                                          preceding the first day of the
                                          relevant Interest Period

       Authorized Denomination:           $1,000

       Initial Redemption Date:           March 28, 2001


         Mississippi  Power Company,  a Mississippi corporation (the "Company",
which term includes any successor corporation under the Indenture referred to on
the  reverse   hereof),   for  value   received,  hereby promises to pay to
_______________________________________________,   or  registered  assigns,  the
principal sum of _________  DOLLARS  ($__________)  on the Stated Maturity shown
above  (or  upon  earlier  redemption),  and to pay  interest  thereon  from the
Original Issue Date shown above, or from the most recent  Interest  Payment Date
to which interest has been paid or duly provided for, monthly in arrears on each
Interest Payment Date as specified  above,  commencing on April 28, 2000, and on
the  Stated  Maturity  (or upon  earlier  redemption)  at the  rates  per  annum
determined in accordance with the provisions specified below until the principal
hereof is paid or made available for payment and on any overdue principal and on
any overdue  installment  of interest.  The interest so payable,  and punctually
paid or duly provided for, on any Interest  Payment Date (other than an Interest
Payment  Date that is the Stated  Maturity or on a  Redemption  Date)  will,  as
provided in such  Indenture,  be paid to the Person in whose name this Note (the
"Note") is  registered  at the close of business  on the Regular  Record Date as
specified  above next  preceding such Interest  Payment Date,  provided that any



interest  payable at Stated  Maturity or on any Redemption  Date will be paid to
the Person to whom  principal is payable.  Except as  otherwise  provided in the
Indenture,  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 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,  if any, on which the Notes of this  series  shall be
listed,  and upon such notice as may be required  by any such  exchange,  all as
more fully provided in the Indenture.

         The Series C Notes (as defined on the reverse hereof) will bear
interest for each  Interest  Period at a per annum rate determined  by the
Calculation Agent, subject to the maximum interest rate permitted by New York or
other applicable state law, as such law may be modified by United States law of
general application.  The interest rate applicable during each Interest Period
will be  equal to LIBOR on the Interest Determination Date for such Interest
Period plus 0.08%; provided, however, that in certain circumstances  described
below, the interest rate will be determined without reference to LIBOR. Promptly
upon such determination,  the Calculation Agent will notify the Company and the
Trustee,  if the Trustee is not then serving as the Calculation Agent, of the
interest rate for the new Interest  Period.  The interest rate determined by the
Calculation Agent,  absent manifest error, shall be binding and conclusive upon
the beneficial owners and  Holders of the Series C Notes,  the Company and the
Trustee.

         If the  following circumstances exist on any Interest Determination
Date, the  Calculation Agent shall determine the interest rate for the Series C
Notes as follows:

                  (1) In the event no Reported Rate appears on Telerate  Page
         3750 as of approximately 11:00  a.m.,  London time, on an Interest
         Determination  Date, the Calculation Agent shall request the principal
         London offices of each of four major banks in the London interbank
         market selected by the Calculation Agent (after consultation with the
         Company) to provide a quotation of the rate (the "Rate Quotation") at
         which one month deposits in amounts of not less than $1,000,000 are
         offered by it to prime banks in the London interbank market, as of
         approximately 11:00 a.m., London time, on such Interest  Determination
         Date, that is representative of single transactions at such time (the
         "Representative Amounts").  If  at  least two Rate Quotations are
         provided, the interest rate will be the arithmetic mean of the Rate
         Quotations obtained by the Calculation Agent, plus 0.08%.

                  (2) In the event no Reported Rate appears on Telerate Page
         3750 as of approximately 11:00  a.m., London time, on an Interest
         Determination Date and there are fewer than two Rate Quotations, the
         interest rate will be the arithmetic mean of the rates quoted at
         approximately 11:00 a.m.,  New York City  time,  on such Interest
         Determination Date,  by three major banks in New York City selected by
         the Calculation Agent (after consultation with the Company),  for loans
         in  Representative Amounts in U. S. dollars to leading European banks,


                                      2


         having an index maturity of one month for a period commencing on the
         second London Business  Day immediately following such Interest
         Determination Date, plus 0.08%;  provided, however, that if fewer than
         three banks selected by the Calculation Agent are quoting such rates,
         the interest rate for the applicable Interest Period will be the same
         as the interest rate in effect for the immediately preceding Interest
         Period.

         "Calculation  Agent" means Bankers Trust Company, or its successor
appointed by the Company, acting as calculation agent.

         "Interest  Determination  Date" means the second  London  Business Day
immediately preceding the first day of the relevant Interest Period.

         "Interest  Period" means the period commencing on an Interest Payment
Date (or, with respect to the initial  Interest Period only,  commencing on the
Original Issue Date) and ending on the day before the next succeeding Interest
Payment Date.

         "LIBOR" for any Interest Determination Date will be the Reported Rate
for deposits in U. S. dollars having an index maturity of one month for a period
commencing on the second London Business Day immediately  following the Interest
Determination Date in amounts of not less than  $1,000,000,  at approximately
11:00 a.m., London time, on the Interest Determination Date.

         "London Business Day" means a day that is a Business Day and a day on
which dealings in deposits in U. S. dollars are transacted, or with respect to
any future date are expected to be transacted, in the London interbank market.

         "Reported Rate" means the rate that appears on Telerate Page 3750 or a
successor  reporter of such rates selected by the Calculation Agent and
acceptable to the Company.

         "Telerate Page 3750" means the display designated on page 3750 on
Bridge Telerate,  Inc. (or such other page as may replace the 3750 page on that
service or such other service as may be nominated by the British Bankers'
Association for the purpose of displaying London interbank offered rates for U.
S. dollar deposits).

         Payments of interest on this Note will include interest accrued to but
excluding the respective Interest Payment Dates. Interest payments for this Note
shall be  computed  and paid on the basis of the actual number of days elapsed
over a 360-day  year. A "Business Day" shall mean any day other than a Saturday
or a  Sunday  or a day on  which banking  institutions in New  York City are
authorized  or required by law or executive order to remain closed or a day on
which the Corporate Trust Office of the Trustee is closed for business.

         Payment of the principal of and interest due at the Stated  Maturity or
earlier  redemption  of the Series C Notes shall be made upon surrender of the
Series C Notes at the  Corporate  Trust Office of the Trustee.  The principal of
and interest on the Series C Notes shall be paid in such coin or currency of the


                                       3


United  States of America as at the time of payment is legal tender for payment
of public and  private  debts.  Payment of  interest  (including  interest on an
Interest Payment Date) will be made, subject to such surrender where applicable,
at the option of the  Company,  (i) by check mailed to the address of the Person
entitled  thereto as such address shall appear in the Security  Register or (ii)
by wire transfer at such place and to such account at a banking  institution  in
the United  States as may be  designated  in writing to the  Trustee at least 16
days prior to the date for payment by the Person entitled thereto.

         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.

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


                                      4








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

Dated:


                                      MISSISSIPPI POWER COMPANY



                                       By:

                                                     Name:
                                                     Title:

Attest:



Assistant Secretary

                             {Seal of MISSISSIPPI POWER COMPANY appears here}














                          CERTIFICATE OF AUTHENTICATION

         This is one of the Senior  Notes  referred  to in the  within-mentioned
Indenture.

                                                     BANKERS TRUST COMPANY,
                                                     as Trustee

                                                     By:
                                                     Title:





                             (Reverse Side of Note)

         This  Note is one of a duly  authorized  issue of  Senior  Notes of the
Company (the "Notes"),  issued and issuable in one or more series under a Senior
Note  Indenture,  dated as of May 1, 1998, as  supplemented  (the  "Indenture"),
between the Company and Bankers Trust  Company,  Trustee (the  "Trustee,"  which
term includes any successor trustee under the Indenture), to which Indenture and
all indentures  incidental  thereto  reference is hereby made for a statement of
the respective rights, limitation of rights, duties and immunities thereunder of
the Company,  the Trustee and the Holders of the Notes issued  thereunder and of
the terms upon which said Notes are, and are to be, authenticated and delivered.
This  Note is one of the  series  designated  on the  face  hereof  as  Series C
Floating  Rate  Senior  Notes due March 28,  2002 (the  "Series C Notes") in the
aggregate principal amount of up to $100,000,000.  Capitalized terms used herein
for which no definition is provided  herein shall have the meanings set forth in
the Indenture.

         The Company shall have the right,  subject to the terms and  conditions
of the Indenture,  to redeem this Note on any Interest  Payment Date on or after
March 28, 2001 at the option of the  Company,  without  premium or  penalty,  in
whole or in part, at a Redemption Price equal to 100% of the principal amount to
be redeemed plus accrued but unpaid interest to the Redemption Date.

         In the event of  redemption  of this Note in part  only,  a new Note or
Notes of this  series for the  unredeemed  portion  hereof will be issued in the
name of the Holder hereof upon the surrender hereof.

         The Series C Notes will not have a sinking fund.

         If an Event of Default  with  respect to the 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,  with the  effect and  subject to the
conditions provided in the Indenture.

         The Indenture permits, with certain exceptions as therein provided, the
amendment  thereof and the  modification  of the rights and  obligations  of the
Company and the rights of the Holders of the Notes of each series to be affected
under the  Indenture at any time by the Company and the Trustee with the consent
of the Holders of not less than a majority in  principal  amount of the Notes at
the time Outstanding of each series to be affected.  The Indenture also contains
provisions  permitting the Holders of specified  percentages in principal amount
of the Notes of each series at the time Outstanding, on behalf of the Holders of
all Notes of such  series,  to waive  compliance  by the  Company  with  certain
provisions of the  Indenture  and certain past defaults  under the Indenture and
their consequences.  Any such consent or waiver by the Holder of this 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  hereof or in lieu  hereof,  whether or not notation of such consent or
waiver is made upon this Note.

         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 interest on this Note at
the times, place and rates, 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 Security  Register,
upon surrender of this Note for registration of transfer at the office or agency
of the Company for such purpose,  duly endorsed by, or  accompanied by a written
instrument  of transfer  in form  satisfactory  to the Company and the  Security
Registrar  and  duly  executed  by,  the  Holder  hereof  or his  attorney  duly
authorized in writing,  and  thereupon one or more new Notes of this series,  of
authorized  denominations and of like tenor and for the same aggregate principal
amount, will be issued to the designated  transferee or transferees.  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.

         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 of a different authorized denomination, as requested by the
Holder surrendering the same upon surrender of the Note or Notes to be exchanged
at the office or agency of the Company.

         This Note shall be governed by, and construed in accordance  with,  the
internal laws of the State of New York.





                                  ABBREVIATIONS

The following  abbreviations,  when used in the  inscription on the face of this
instrument, shall be construed as though they were written out in full according
to applicable laws or regulations:







TEN COM- as tenants in       UNIF GIFT MIN ACT- _______ Custodian ________
         common                                         (Cust)       (Minor)
TEN ENT- as tenants by the
         entireties                                   under Uniform Gifts to
 JT TEN- as joint tenants                             Minors Act
         with right of
         survivorship and                              ________________________
         not as tenants                                  (State)
         in common


                    Additional abbreviations may also be used
                          though not on the above list.


        FOR VALUE RECEIVED, the undersigned hereby sell(s) and transfer(s) unto
_______________________________________________________________________________
(please insert Social Security or other identifying number of assignee)

_______________________________________________________________________________
PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE OF
ASSIGNEE

_______________________________________________________________________________

________________________________________________________________________________
the within Note and all rights thereunder, hereby irrevocably constituting and
appointing

_______________________________________________________________________________

_______________________________________________________________________________
agent to  transfer  said Note on the books of the  Company,  with full  power of
substitution in the premises.

Dated:  _______________________



                                 NOTICE:   The signature to this assignment
                                           must correspond with the name as
                                           written upon the face of the within
                                           instrument in every particular
                                           without alteration or enlargement, or
                                           any change whatever.




                                    EXHIBIT B

                          CERTIFICATE OF AUTHENTICATION

         This is one of the Senior Notes referred to in the within-mentioned
Indenture.

                                                     BANKERS TRUST COMPANY,
                                                     as Trustee

                                                     By:
                                                     Title: