<PAGE>

                                                     Registration No. 333-______
                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549


                                   Form S-8
                            REGISTRATION STATEMENT
                                     Under
                          THE SECURITIES ACT OF 1933

                               OLIN CORPORATION
            (Exact name of registrant as specified in its charter)

                 Virginia                                  13-1872319
                 --------                                  -----------
       (State or other jurisdiction                     (I.R.S. Employer
     of incorporation or organization)                 Identification No.)

        501 Merritt 7, Norwalk, Connecticut                   06856
        ------------------------------------------------------------------
     (Address of Principal Executive Offices)               (Zip Code)

                      OLIN 1991 LONG TERM INCENTIVE PLAN
                           (Full title of the plan)

                              J. M. Jackson, Jr.
                        Vice President, General Counsel
                                 and Secretary

                               Olin Corporation
                                 501 Merritt 7
                          Norwalk, Connecticut  06851
                    (Name and address of agent for service)

                                 203-750-3126
         (Telephone number, including area code, of agent for service)

                        CALCULATION OF REGISTRATION FEE
--------------------------------------------------------------------------------
<TABLE>
<CAPTION>
                                                           Proposed maximum      Proposed maximum
Title of securities                      Amount to be      offering price        aggregate offering      Amount of
to be registered                          registered       per share             price                   registration fee
-------------------                      ------------      ----------------      ------------------      ----------------
<S>                                      <C>               <C>                   <C>                     <C>
Common Stock, par value $1.00             317,674(1)       $15.59375(2)          $4,953,728.9375(2)          $1,308.00

Common Stock, par value $1.00             439,671(3)             N/A(3)                      N/A(3)             N/A(3)

Series A Participating Cumulative
  Preferred Stock Purchase Rights             (1)(4)             N/A(4)                      N/A(4)             N/A(4)
</TABLE>
_________________________
(1)  Plus an indefinite additional number of shares as may be issued as the
     result of stock dividends, stock splits or as the result of the anti-
     dilution provisions of the Olin 1991 Long Term Incentive Plan.

(2)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(h) and (c) under the Securities Act of 1933, as
     amended, and based on the average of the high and low prices of Olin
     Corporation Common Stock reported on the New York Stock Exchange
     consolidated reporting system on February 22, 2000.

(3)  Additional shares issuable under the Olin 1991 Long Term Incentive Plan as
     the result of a two-for-one stock split in October 1996, previously
     reported on Form 8-K.  Pursuant to Rule 416(b), no fee is due for such
     shares.

(4)  The Rights are appurtenant to and trade with the Common Stock.  The value
     attributable to the Rights, if any, is reflected in the value of the Common
     Stock and the registration fee for the Rights is included in the fee for
     the Common Stock.

<PAGE>

                               EXPLANATORY NOTE

     This Registration Statement is being filed by Olin Corporation to add the
following securities to the Registration Statement on Form S-8, Registration No.
33-40346, filed May 2, 1991:

     1.  317,674 shares representing shares issuable under the Plan pursuant to
adjustments made in accordance with the anti-dilution provisions of the Plan in
connection with the spin-off of two subsidiaries; and

     2.  439,671 shares representing shares issuable under the Plan pursuant to
an October 1996 stock split, which stock split was previously reported by Olin
Corporation on a Form 8-K filing.

     Pursuant to Instruction E of Form S-8, the contents of the Company's
Registration Statement on Form S-8 filed with the Securities and Exchange
Commission on May 2, 1991 (File No. 33-40346) relating to the registration of
500,000 shares, is incorporated by reference in its entirety in this
Registration Statement, except as to the items provided herein.

                                    Part II

Item 3.   INCORPORATION OF DOCUMENTS BY REFERENCE
          ---------------------------------------

          The SEC allows us to incorporate by reference the information we file
with them, which means:

          -    incorporated documents are considered part of the prospectus;

          -    we can disclose important information to you by referring you to
               those documents; and

          -    information that we file with the SEC will automatically update
               and supersede this incorporated information.

          We incorporate by reference the documents listed below which were
filed with the SEC under the Securities Exchange Act of 1934:

          (a)  Our Annual Report on Form 10-K for the fiscal year ended December
               31, 1998;

          (b)  Our Quarterly Reports on Form 10-Q for the fiscal quarters ended
               March 31, 1999, June 30, 1999 and September 30, 1999;

          (c)  The description of the Common Stock, par value $1.00 per share,
               of the Company, contained in the Company's Quarterly Report on
               Form 10-Q for the fiscal quarter ended September 30, 1991; and

          (d)  The description of the Series A Participating Cumulative
               Preferred Stock Purchase Rights of the Company, contained in the
               Company's Form 8-A dated February 21, 1996.


                                       2
<PAGE>

          We also incorporate by reference each of the following documents that
we will file with the SEC after the date of this registration statement until
this offering is completed:

          -    reports filed under Section 13(a) and (c) of the Securities
               Exchange Act of 1934;

          -    definitive proxy or information statements filed under Section 14
               of the Securities Exchange Act of 1934 in connection with any
               subsequent stockholders' meeting; and

          -    any reports filed under Section 15(d) of the Securities Exchange
               Act of 1934.


Item 5.   INTEREST OF NAMED EXPERTS AND COUNSEL
          -------------------------------------

     The validity of the newly issued shares of Common Stock of the Company will
be passed upon by J. M. Jackson, Vice President, General Counsel and Secretary.
Mr. Jackson owns shares of the Company directly, through various employee
benefit plans and has options to purchase shares.

Item 6.   INDEMNIFICATION OF DIRECTORS AND OFFICERS
          -----------------------------------------

     The Virginia Stock Corporation Act permits indemnification of the Company's
directors, officers and employees in a variety of circumstances. Under Section
13.1-697 of the Virginia Stock Corporation Act, a Virginia corporation generally
is authorized to indemnify its directors, officers and employees in civil or
criminal actions if they acted in good faith and believed their conduct to be in
the best interests of the corporation. In the case of criminal actions,
directors, officers or employees will be indemnified if they had no reasonable
cause to believe that their conduct was unlawful. The Act also provides
mandatory indemnification in Section 13.1-698 for a director against expenses
incurred in the successful defense of a proceeding. Under Section 13.1-704 of
the Virginia Stock Corporation Act, a Virginia corporation is permitted to grant
further indemnity to its directors, officers and employees as may be authorized
by the articles of incorporation or any bylaw unless those persons provided
indemnity engaged in willful misconduct or a knowing violation of the criminal
law. The Company's By-laws require indemnification of directors, officers and
employees with respect to certain liabilities, expenses and other amounts
imposed upon them by reason of having been directors, officers or employees
unless they engaged in willful misconduct or a knowing violation of the criminal
law. The Company's Board of Directors or legal counsel make the determination of
whether a director, officer or employee met the standard of conduct required for
indemnification. Section 13.1-692.1 of the Virginia Stock Corporation Act
permits a Virginia corporation to limit or totally eliminate the liability of a
director or officer in a shareholder or derivative proceeding unless that
director or officer engaged in willful misconduct or a knowing violation of the
criminal law or securities laws. The Company's By-laws contain a provision
intended to eliminate such liability.

     Directors and officers of the Company are insured, subject to certain
exclusions and limits and to the extent not otherwise indemnified by the
Company, against loss (including expenses incurred in the defense of actions,
suits and proceedings in connection therewith)


                                       3
<PAGE>

arising from any error, misstatement, misleading statement, omission or other
act made or performed in their capacity as directors and officers. The policies
also reimburse the Company for liability incurred in the indemnification of its
directors and officers under common or statutory laws or the Company's By-laws,
subject to the terms, conditions and exclusions of such policies. In addition,
directors, officers and other employees of the Company who may be "fiduciaries"
as that term is used in the Employee Retirement Income Security Act of 1974 are
insured with respect to liabilities under the Act.

Item 7.   EXHIBITS
          --------

     The Exhibits to this Registration Statement are listed in the Exhibit Index
to this Registration Statement, which Index is incorporated herein by reference.


                                  SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement on Form S-8 to be signed on its behalf by the undersigned, thereunto
duly authorized, in the Town of Norwalk, State of Connecticut, on the 24th day
of February, 2000.

                                       OLIN CORPORATION

                                       By: /s/ J. M. Jackson, Jr.
                                          ---------------------------------
                                               J. M. Jackson, Jr.
                                       Title:  Vice President, General Counsel
                                               and Secretary


                               POWER OF ATTORNEY

     KNOW ALL MEN BY THESE PRESENTS that each individual whose signature appears
below constitutes and appoints J. M. Jackson and A. W. Ruggiero, and each of
them, his/her true and lawful attorneys-in-fact and agents with full power of
substitution, for him/her and in his/her name, place and stead, in any and all
capacities, to sign any and all amendments (including post-effective amendments)
to this Registration Statement and any other documents and instruments
incidental thereto, and to file the same, with all exhibits thereto, and all
documents in connection therewith, with the Securities and Exchange Commission,
granting unto said attorneys-in-fact and agents, and each of them, full power
and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as he/she might or could do in person, thereby ratifying and confirming
all that said attorneys-in-fact and agents and/or any of them, or their or
his/her substitute or substitutes, may lawfully do or cause to be done by virtue
hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.


                                       4
<PAGE>

<TABLE>
<CAPTION>
          Signature              Title                                         Date
          ---------              -----                                         ----
<S>                              <C>                                     <C>

/s/ Donald W. Griffin            Chairman of the Board, President,       February 24, 2000
-----------------------------    Chief Executive Officer and Director
Donald W. Griffin                (Principal Executive Officer)


/s/ Anthony W. Ruggiero          Executive Vice President, Chief         February 24, 2000
-----------------------------    Financial Officer and Director
Anthony W. Ruggiero              (Principal Financial Officer)



/s/ William W. Higgins           Director                                February 24, 2000
-----------------------------
William W. Higgins


                                 Director
-----------------------------
 Suzanne D. Jaffe


/s/ G. Jackson Ratcliffe, Jr.    Director                                February 24, 2000
-----------------------------
G. Jackson Ratcliffe, Jr.


/s/ Randall W. Larrimore         Director                                February 24, 2000
-----------------------------
Randall W. Larrimore


/s/ Richard M. Rompala           Director                                February 24, 2000
-----------------------------
Richard M. Rompala


/s/ Mary E. Gallagher            Controller (Principal Accounting        February 24, 2000
-----------------------------    Officer)
Mary E. Gallagher
</TABLE>



                                       5
<PAGE>

                                 EXHIBIT INDEX

Exhibit
Number       Description of Documents
-------      ------------------------

5            Opinion of Counsel.

23.1         Consent of Independent Auditor.

23.2         Consent of Counsel (included in Exhibit 5).

24           Power of Attorney (included on Signature Page of the
             Registration Statement).
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 14810}]
{"company-data": {"conformed-name": "OLIN CORP", "cik": "0000074303", "assigned-sic": "2800", "irs-number": "131872319", "state-of-incorporation": "VA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-31096", "film-number": "553105"}, "business-address": {"street1": "501 MERRITT 7", "street2": "P O BOX 4500", "city": "NORWALK", "state": "CT", "zip": "06856", "phone": "2037503000"}, "mail-address": {"street1": "OLIN CORP", "street2": "501 MERRITT 7 PO BOX 4500", "city": "NORWALK", "state": "CT", "zip": "06851"}, "former-company": {"former-conformed-name": "OLIN MATHIESON CHEMICAL CORP", "date-changed": "19691008"}}
Registration No. 333-______
                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                   Form S-8
                            REGISTRATION STATEMENT
                                     Under
                          THE SECURITIES ACT OF 1933

                               OLIN CORPORATION
            (Exact name of registrant as specified in its charter)

                 Virginia                                  13-1872319
                 --------                                  -----------
       (State or other jurisdiction                     (I.R.S. Employer
     of incorporation or organization)                 Identification No.)

        501 Merritt 7, Norwalk, Connecticut                   06856
        ------------------------------------------------------------------
     (Address of Principal Executive Offices)               (Zip Code)

                      OLIN 1991 LONG TERM INCENTIVE PLAN
                           (Full title of the plan)

                              J. M. Jackson, Jr.
                        Vice President, General Counsel
                                 and Secretary

                               Olin Corporation
                                 501 Merritt 7
                          Norwalk, Connecticut  06851
                    (Name and address of agent for service)

                                 203-750-3126
         (Telephone number, including area code, of agent for service)

                        CALCULATION OF REGISTRATION FEE
--------------------------------------------------------------------------------
Proposed maximum      Proposed maximum
Title of securities                      Amount to be      offering price        aggregate offering      Amount of
to be registered                          registered       per share             price                   registration fee
-------------------                      ------------      ----------------      ------------------      ----------------
Common Stock, par value $1.00             317,674(1)       $15.59375(2)          $4,953,728.9375(2)          $1,308.00

Common Stock, par value $1.00             439,671(3)             N/A(3)                      N/A(3)             N/A(3)

Series A Participating Cumulative
  Preferred Stock Purchase Rights             (1)(4)             N/A(4)                      N/A(4)             N/A(4)
_________________________
(1)  Plus an indefinite additional number of shares as may be issued as the
     result of stock dividends, stock splits or as the result of the anti-
     dilution provisions of the Olin 1991 Long Term Incentive Plan.

(2)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(h) and (c) under the Securities Act of 1933, as
     amended, and based on the average of the high and low prices of Olin
     Corporation Common Stock reported on the New York Stock Exchange
     consolidated reporting system on February 22, 2000.

(3)  Additional shares issuable under the Olin 1991 Long Term Incentive Plan as
     the result of a two-for-one stock split in October 1996, previously
     reported on Form 8-K.  Pursuant to Rule 416(b), no fee is due for such
     shares.

(4)  The Rights are appurtenant to and trade with the Common Stock.  The value
     attributable to the Rights, if any, is reflected in the value of the Common
     Stock and the registration fee for the Rights is included in the fee for
     the Common Stock.
EXPLANATORY NOTE

     This Registration Statement is being filed by Olin Corporation to add the
following securities to the Registration Statement on Form S-8, Registration No.
33-40346, filed May 2, 1991:

     1.  317,674 shares representing shares issuable under the Plan pursuant to
adjustments made in accordance with the anti-dilution provisions of the Plan in
connection with the spin-off of two subsidiaries; and

     2.  439,671 shares representing shares issuable under the Plan pursuant to
an October 1996 stock split, which stock split was previously reported by Olin
Corporation on a Form 8-K filing.

     Pursuant to Instruction E of Form S-8, the contents of the Company's
Registration Statement on Form S-8 filed with the Securities and Exchange
Commission on May 2, 1991 (File No. 33-40346) relating to the registration of
500,000 shares, is incorporated by reference in its entirety in this
Registration Statement, except as to the items provided herein.

                                    Part II

Item 3.   INCORPORATION OF DOCUMENTS BY REFERENCE
          ---------------------------------------

          The SEC allows us to incorporate by reference the information we file
with them, which means:

          -    incorporated documents are considered part of the prospectus;

          -    we can disclose important information to you by referring you to
               those documents; and

          -    information that we file with the SEC will automatically update
               and supersede this incorporated information.

          We incorporate by reference the documents listed below which were
filed with the SEC under the Securities Exchange Act of 1934:

          (a)  Our Annual Report on Form 10-K for the fiscal year ended December
               31, 1998;

          (b)  Our Quarterly Reports on Form 10-Q for the fiscal quarters ended
               March 31, 1999, June 30, 1999 and September 30, 1999;

          (c)  The description of the Common Stock, par value $1.00 per share,
               of the Company, contained in the Company's Quarterly Report on
               Form 10-Q for the fiscal quarter ended September 30, 1991; and

          (d)  The description of the Series A Participating Cumulative
               Preferred Stock Purchase Rights of the Company, contained in the
               Company's Form 8-A dated February 21, 1996.

                                       2
We also incorporate by reference each of the following documents that
we will file with the SEC after the date of this registration statement until
this offering is completed:

          -    reports filed under Section 13(a) and (c) of the Securities
               Exchange Act of 1934;

          -    definitive proxy or information statements filed under Section 14
               of the Securities Exchange Act of 1934 in connection with any
               subsequent stockholders' meeting; and

          -    any reports filed under Section 15(d) of the Securities Exchange
               Act of 1934.

Item 5.   INTEREST OF NAMED EXPERTS AND COUNSEL
          -------------------------------------

     The validity of the newly issued shares of Common Stock of the Company will
be passed upon by J. M. Jackson, Vice President, General Counsel and Secretary.
Mr. Jackson owns shares of the Company directly, through various employee
benefit plans and has options to purchase shares.

Item 6.   INDEMNIFICATION OF DIRECTORS AND OFFICERS
          -----------------------------------------

     The Virginia Stock Corporation Act permits indemnification of the Company's
directors, officers and employees in a variety of circumstances. Under Section
13.1-697 of the Virginia Stock Corporation Act, a Virginia corporation generally
is authorized to indemnify its directors, officers and employees in civil or
criminal actions if they acted in good faith and believed their conduct to be in
the best interests of the corporation. In the case of criminal actions,
directors, officers or employees will be indemnified if they had no reasonable
cause to believe that their conduct was unlawful. The Act also provides
mandatory indemnification in Section 13.1-698 for a director against expenses
incurred in the successful defense of a proceeding. Under Section 13.1-704 of
the Virginia Stock Corporation Act, a Virginia corporation is permitted to grant
further indemnity to its directors, officers and employees as may be authorized
by the articles of incorporation or any bylaw unless those persons provided
indemnity engaged in willful misconduct or a knowing violation of the criminal
law. The Company's By-laws require indemnification of directors, officers and
employees with respect to certain liabilities, expenses and other amounts
imposed upon them by reason of having been directors, officers or employees
unless they engaged in willful misconduct or a knowing violation of the criminal
law. The Company's Board of Directors or legal counsel make the determination of
whether a director, officer or employee met the standard of conduct required for
indemnification. Section 13.1-692.1 of the Virginia Stock Corporation Act
permits a Virginia corporation to limit or totally eliminate the liability of a
director or officer in a shareholder or derivative proceeding unless that
director or officer engaged in willful misconduct or a knowing violation of the
criminal law or securities laws. The Company's By-laws contain a provision
intended to eliminate such liability.

     Directors and officers of the Company are insured, subject to certain
exclusions and limits and to the extent not otherwise indemnified by the
Company, against loss (including expenses incurred in the defense of actions,
suits and proceedings in connection therewith)

                                       3
arising from any error, misstatement, misleading statement, omission or other
act made or performed in their capacity as directors and officers. The policies
also reimburse the Company for liability incurred in the indemnification of its
directors and officers under common or statutory laws or the Company's By-laws,
subject to the terms, conditions and exclusions of such policies. In addition,
directors, officers and other employees of the Company who may be "fiduciaries"
as that term is used in the Employee Retirement Income Security Act of 1974 are
insured with respect to liabilities under the Act.

Item 7.   EXHIBITS
          --------

     The Exhibits to this Registration Statement are listed in the Exhibit Index
to this Registration Statement, which Index is incorporated herein by reference.

                                  SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement on Form S-8 to be signed on its behalf by the undersigned, thereunto
duly authorized, in the Town of Norwalk, State of Connecticut, on the 24th day
of February, 2000.

                                       OLIN CORPORATION

                                       By: /s/ J. M. Jackson, Jr.
                                          ---------------------------------
                                               J. M. Jackson, Jr.
                                       Title:  Vice President, General Counsel
                                               and Secretary

                               POWER OF ATTORNEY

     KNOW ALL MEN BY THESE PRESENTS that each individual whose signature appears
below constitutes and appoints J. M. Jackson and A. W. Ruggiero, and each of
them, his/her true and lawful attorneys-in-fact and agents with full power of
substitution, for him/her and in his/her name, place and stead, in any and all
capacities, to sign any and all amendments (including post-effective amendments)
to this Registration Statement and any other documents and instruments
incidental thereto, and to file the same, with all exhibits thereto, and all
documents in connection therewith, with the Securities and Exchange Commission,
granting unto said attorneys-in-fact and agents, and each of them, full power
and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as he/she might or could do in person, thereby ratifying and confirming
all that said attorneys-in-fact and agents and/or any of them, or their or
his/her substitute or substitutes, may lawfully do or cause to be done by virtue
hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.

                                       4
Signature              Title                                         Date
          ---------              -----                                         ----
/s/ Donald W. Griffin            Chairman of the Board, President,       February 24, 2000
-----------------------------    Chief Executive Officer and Director
Donald W. Griffin                (Principal Executive Officer)

/s/ Anthony W. Ruggiero          Executive Vice President, Chief         February 24, 2000
-----------------------------    Financial Officer and Director
Anthony W. Ruggiero              (Principal Financial Officer)

/s/ William W. Higgins           Director                                February 24, 2000
-----------------------------
William W. Higgins

                                 Director
-----------------------------
 Suzanne D. Jaffe

/s/ G. Jackson Ratcliffe, Jr.    Director                                February 24, 2000
-----------------------------
G. Jackson Ratcliffe, Jr.

/s/ Randall W. Larrimore         Director                                February 24, 2000
-----------------------------
Randall W. Larrimore

/s/ Richard M. Rompala           Director                                February 24, 2000
-----------------------------
Richard M. Rompala

/s/ Mary E. Gallagher            Controller (Principal Accounting        February 24, 2000
-----------------------------    Officer)
Mary E. Gallagher
5
EXHIBIT INDEX

Exhibit
Number       Description of Documents
-------      ------------------------

5            Opinion of Counsel.

23.1         Consent of Independent Auditor.

23.2         Consent of Counsel (included in Exhibit 5).

24           Power of Attorney (included on Signature Page of the
             Registration Statement).