<PAGE>

                                                                    Exhibit 4.15

      [Form of Certificated Fixed Rate Registered Security--United States]

                                 [Form of Face]

NOTE NUMBER ___                   AGENTS NAME


                                                                    ASHLAND INC.

- ----------------------------------------------------
PRINCIPAL AMOUNT     SETTLEMENT DATE      TRADE DATE



U.S.$               (ORIGINAL ISSUE DATE)



- --------------------------------------------------------------------------------
MATURITY DATE  TRUSTEE'S CUST. NO.  INTEREST RATE   XPAYER ID      TRANSFERRED
                                                    OR SOC. SEC.
                                                      NO. OF

- --------------------------------------------------------------------------------
NAME AND ADDRESS OF REGISTERED OWNER               MEDIUM-TERM
                                                      NOTE
                                                    PROGRAM

                                           U.S. BANK, NATIONAL ASSOCIATION
                                                     TRUSTEE


CUSTOMER'S   RETAIN FOR     THE TIME OF THE        PLEASE SIGN           SEE
   COPY     TAX PURPOSES  TRANSACTION WILL BE       AND RETURN      REVERSE SIDE
                         FURNISHED UPON REQUEST     ENCLOSED
                            OF THE CUSTOMER          RECEIPT
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------







<PAGE>

REGISTERED                                                            REGISTERED

                                  ASHLAND INC.
                           MEDIUM-TERM NOTE, SERIES K
                   Due Nine Months or More From Date Of Issue
NO.      ___                     (Fixed Rate)                              U.S.$


                                                     CUSIP
ORIGINAL ISSUE DATE:                INTEREST RATE:   MATURITY DATE:


REDEMPTION DATE:             INDEXED NOTES:        YES (see attached)         NO

OTHER PROVISIONS:


     ASHLAND INC., a corporation duly organized and existing under the laws of
Kentucky (herein called 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

     U.S. DOLLARS, on the Maturity Date specified above, and to pay interest
thereon from the Original Issue Date specified above, or from the most recent
Interest Payment Date to which interest has been paid or duly provided for, to
but excluding the relevant Interest Payment Date, semiannually in arrears on
February 15 and August 15 in each year, unless otherwise indicated in the
applicable pricing supplement, commencing on the first such date after the
Original Issue Date set forth above, at the rate set forth on the face hereof,
until the principal hereof is paid or made available for payment; provided,
                                                                  --------
however, that if the Original Issue Date set forth above is after a Regular
- -------
Record Date referred to below and before the related Interest Payment Date, the
first payment of interest will be made on the Interest Payment Date following
the next succeeding Regular Record Date. The interest so payable, and punctually
paid or duly provided for, on any Interest Payment Date (other than at Maturity)
will, as provided in such Indenture, be paid to the Person in whose name this
Security (or one or more Predecessor Securities) is registered at the close of
business on the Regular Record Date for such interest, which shall be the
February 1 or August 1 (whether or not a Business Day), unless otherwise
indicated in the applicable pricing supplement, as the case may be, next
preceding such Interest Payment Date; provided, however, that interest payable
                                      --------  -------
at Maturity shall be payable to the Person to whom principal shall be 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 Security (or one or more Predecessor Securities) is registered at the
close of business on a Special Record Date for the payment of such Defaulted
Interest to be fixed by the Trustee, notice whereof shall be given to Holders of
Securities of this series not less than 10 days

<PAGE>

prior to such Special Record Date, or be paid at any time in any other lawful
manner not inconsistent with the requirements of any securities exchange on
which the Securities of this series may be listed, and upon such notice as may
be required by such exchange, all as more fully provided in said Indenture.
Payment of the principal, premium, if any, and interest on this Security will be
made at the principal corporate trust office of the Trustee in Cincinnati, Ohio,
or such other office or agency of the Company as may be designated by it for
such purpose in Cincinnati, Ohio (the "Paying Agent"), in such coin or currency
of the United States of America as at the time of payment is legal tender for
payment of public and private debts; provided, however, that at the option of
                                     --------  -------
the Company, payment of interest (except at Maturity) may be made by United
States dollar check mailed to the address of the Person entitled thereto as such
address shall appear in the Security Register. Payment of the principal,
premium, if any, and interest on this Security due at Maturity will be made in
immediately available funds upon surrender of this Security to the Paying Agent;
provided that this Security is presented to the Paying Agent in time for the
- --------
Paying Agent to make such payment in accordance with its normal procedures.
"Maturity" shall mean the date on which the principal of this Security or an
installment of principal becomes due, whether on the Maturity Date specified
above, upon redemption or otherwise.

     REFERENCE IS HEREBY MADE TO THE FURTHER PROVISIONS OF THIS SECURITY SET
FORTH IN FULL ON THE REVERSE HEREOF, WHICH FURTHER PROVISIONS SHALL FOR ALL
PURPOSES HAVE THE SAME EFFECT AS IF SET FORTH IN FULL AT THIS PLACE.

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof, directly or through an Authenticating
Agent, by manual signature of an authorized officer, this Security shall not be
entitled to any benefit under the Indenture or be valid or obligatory for any
purpose.

<PAGE>

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

Dated:                              ASHLAND INC.

                                    By:
                                           _____________________  ______________
                                           Treasurer

[Seal]                              Attest:

                                           _____________________  ______________
                                           Assistant Secretary

                     TRUSTEE'S CERTIFICATE OF AUTHENTICATION

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

U.S. BANK, National Association
     As Trustee

By:
     ________________________________
       Authorized Signatory







<PAGE>

                                [Form of Reverse]

                                  ASHLAND INC.
                           MEDIUM-TERM NOTE, SERIES K

                                  (Fixed Rate)

     This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities"), issued and to be issued in one or more
series under an Indenture, dated as of (herein called the "Indenture"), between
the Company and U.S. Bank, National Association, as Trustee (herein called the
"Trustee", which term includes any successor trustee under the Indenture), to
which Indenture and all indentures supplemental thereto reference is hereby made
for a statement of the respective rights, limitations of rights, duties and
immunities thereunder of the Company, the Trustee and the Holders of the
Securities and of the terms upon which the securities are, and are to be,
authenticated and delivered. This Security is one of the series designated on
the face hereof.

     This Security may not be redeemed prior to the Redemption Date set forth on
the face hereof. If no Redemption Date is so set forth, this Security is not
redeemable prior to the Maturity Date. On or after the Redemption Date set forth
on the face hereof, this Security is redeemable in whole or in part in
increments of U.S. $1,000 at the option of the Company at a redemption price
equal to 100% of the principal amount to be redeemed together with interest
thereon to the date of redemption.

     Notice of redemption will be given by mail to Holders of Securities, not
more than 60 nor less than 30 days prior to the date fixed for redemption, all
as provided in the Indenture.

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

     The Securities of this series will not have a sinking fund unless otherwise
specified in the applicable pricing supplement.

     Subject to a number of important qualifications and exceptions set forth in
the Indenture, the Indenture provides that neither the Company nor any
Subsidiary (as defined in the Indenture) will (i) issue, assume or guarantee any
notes, bonds, debentures or other similar evidences of indebtedness for money
borrowed secured by a mortgage, lien, pledge or other encumbrance upon any real
or personal property located in the continental United States of America without
effectively providing that the Securities will be secured equally and ratably
with (or, at the option of the Company, prior to) such indebtedness so long as
such indebtedness shall be so secured or (ii) enter into any Sale and Lease-Back
Transactions (as defined in the Indenture).

<PAGE>

     The Indenture also provides that the Company at its option (a) will be
Discharged (as such term is defined in the Indenture) from any and all
obligations in respect of the Securities (except for certain obligations to
register the transfer or exchange of Securities, replace stolen, lost or
mutilated Securities, maintain paying agencies and hold moneys for payment in
trust) or (b) need not comply with certain restrictive covenants of the
Indenture, if there is deposited with the Trustee, in the case of Securities
Denominated in U.S. dollars, U.S. Government Obligations (as defined in the
Indenture) or, in the case of Securities denominated in a foreign currency,
Foreign Government Securities (as defined in the Indenture), which through the
payment of interest thereon and principal thereof in accordance with their terms
will provide money or a combination of money and U.S. Government Obligations or
Foreign Government Securities, as the case may be, in an amount sufficient to
pay in the currency, currencies or currency unit or units in which the
Securities are payable all the principal, premium, if any, and interest on, the
Securities on the dates such payments are due in accordance with the terms of
the Securities.

     Interest payments for this Security will include interest accrued to but
excluding the Interest Payment Date. Interest payments for this Security shall
be computed and paid on the basis of a 360-day year of twelve 30-day months.

     The interest rate on this Security will in no event be higher than the
maximum rate permitted by New York law as the same may be modified by United
States law of general applicability.

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

     The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities of each series to be
affected under the Indenture at any time by the Company and the Trustee with the
consent of the Holders of 66 2/3% in principal amount of the Securities 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 Securities of each series at the time Outstanding, on behalf of the
Holders of all Securities of such series, to waive compliance by the Company
with certain provisions of the Indenture and certain past defaults under the
Indenture and their consequences. Any such consent or waiver by the Holder of
this Security shall be conclusive and binding upon such Holder and upon all
future Holders of this Security and of any Security issued upon the registration
of transfer hereof or in exchange herefor or in lieu hereof, whether or not
notation of such consent or waiver is made upon this Security.

     As set forth in, and subject to, the provisions of the Indenture, no Holder
of any Security of this series will have any right to institute any proceeding
with respect to the Indenture or for any remedy thereunder, unless such Holder
shall have previously given to the Trustee written notice of a continuing Event
of Default with respect to this series, the Holders of not less than 25% in
principal amount of the Outstanding Securities of this series shall have made
written request, and offered reasonable indemnity, to the Trustee to institute

<PAGE>

such proceeding as trustee, the Trustee shall not have received from the Holders
of a majority in principal amount of the Outstanding Securities of this series a
direction inconsistent with such request and the Trustee shall have failed to
institute such proceeding within 60 days; provided, however, that such
                                          --------  -------
limitations do not apply to a suit instituted by the Holder hereof for the
enforcement of payment of the principal, premium, if any, or interest on this
Security on or after the respective due dates expressed herein.

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

     As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Security is registrable in the Security Register,
upon surrender of this Security for registration of transfer at the corporate
trust office of the Trustee or such other office or agency as may be designated
by the Company in Cincinnati, Ohio, duly endorsed by, or accompanied by a
written instrument of transfer in form satisfactory to the Company and the
Security Registrar duly executed by, the Holder hereof or his attorney duly
authorized in writing, and thereupon one or more new Securities of this series
and of like tenor, of authorized denominations and with like terms and
conditions and for the same aggregate principal amount, will be issued to the
designated transferee or transferees.

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

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

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

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

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

<PAGE>


                                  _____________

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

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

                                  _____________



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

Please Insert Social Security or Other
   Identifying Number of Assignee

______________________________________________



______________________________________________


                                               _________________________________


________________________________________________________________________________

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



the within Security and all rights thereunder, hereby irrevocably constituting
and appointing ________________________________________________ attorney

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

Dated:______________________   _________________________________________________
                                                  Signature







