<PAGE>
 
   As filed with the Securities and Exchange Commission on September 9, 1997

                                                 Registration No. 33-___________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549


                                   FORM S-8

            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933


                           CROSS TIMBERS OIL COMPANY
            (Exact name of registrant as specified in its charter)


         Delaware                                           75-2347769
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                           Identification No.)

810 Houston Street, Suite 2000, Fort Worth, Texas              76102
    (Address of Principal Executive Offices)                 (Zip Code)


              CROSS TIMBERS OIL COMPANY 1994 STOCK INCENTIVE PLAN
                           (Full title of the plan)

                              Mr. Bob R. Simpson
                        810 Houston Street, Suite 2000
                           Fort Worth, Texas  76102
                    (Name and address of agent for service)

                                (817) 870-2800
         (Telephone number, including area code, of agent for service)

                                  ----------

                                   Copy to:

                          KELLY, HART & HALLMAN, P.C.
                          201 Main Street, Suite 2500
                           Fort Worth, Texas  76102
                        Attn: F. Richard Bernasek, Esq.

<TABLE> 
<CAPTION> 
                        Calculation of Registration Fee
================================================================================
                                           Proposed    Proposed               
                               Amount      maximum     maximum                
                                to be      offering   aggregate     Amount of 
  Title of securities        registered   price per    offering   registration
   to be registered              (1)      share (2)      price       fee (2)
- ------------------------------------------------------------------------------
<S>                          <C>          <C>         <C>         <C>
Common Stock, $.01 par          300,000    $21.4375   $6,431,250     $1,948.86
 value                          shares

</TABLE>

- ---------
(1)  Pursuant to Rule 416(a), the number of shares of Common Stock registered
     hereunder includes such indeterminate number of additional shares of Common
     Stock as may be offered or issued to prevent dilution resulting from stock
     splits, stock dividends or similar transactions.

(2)  Computed pursuant to Rules 457 (c) and (h) based on the average of the
     high and low prices on September 4, 1997.

================================================================================
<PAGE>
 
                                    PART II
              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


This Registration Statement registers additional securities to be issued under
the Cross Timbers Oil Company 1994 Stock Incentive Plan.  The contents of the
prior Registration Statement on Form S-8, Registration No. 33-81766, are hereby
incorporated by reference in this Registration Statement.


Item 8.  Exhibits.

     Exhibit Number                                                      Page
     and Description                                                    Number
     ---------------                                                    ------

     (4)   Instruments defining the rights of security holders, 
           including indentures

           4.1   Cross Timbers Oil Company 1994 Stock Incentive Plan, 
                 as amended and restated on May 21, 1996

     (5)   Opinion re legality

           5.1   Kelly, Hart & Hallman, P.C.

     (15)  Letter re unaudited interim financial information

           15.1  Awareness letter of Arthur Andersen LLP

     (23)  Consents of experts and counsel

           23.1  Consent of Arthur Andersen LLP
           23.2  Consent of Kelly, Hart & Hallman, P.C. (included in 
                 its opinion filed as Exhibit 5.1)

     (24)  Power of attorney (included on page 4 of the Registration
            Statement)



                                      -2-
<PAGE>
 
                                  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 to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Fort Worth, State of Texas, on September 9, 1997.


                                       CROSS TIMBERS OIL COMPANY


                                       By:  BOB R. SIMPSON
                                          ------------------------------
                                            Bob R. Simpson
                                            Chairman and Chief Executive Officer




                                      -3-
<PAGE>
 
                               POWER OF ATTORNEY

     KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Bob R. Simpson and Steffen E. Palko, and each of
them, his true and lawful attorneys-in-fact and agents, with full power of
substitution and resubstitution, for him in his name, place and stead, in any
and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits hereto, and other 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, as fully to all intents
and purposes as he might or could do in person, hereby ratifying and confirming
all that said attorneys-in-fact and agents or either of them, or their or his
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 dates indicated.

<TABLE>
<CAPTION>
 
     Signature                      Title                          Date
     ---------                      -----                          ----
<S>                          <C>                             <C>
                                                      
BOB R. SIMPSON               Chairman of the Board;          September 9, 1997
- -----------------------       Executive Officer;      
Bob R. Simpson                Director (Principal                        
                              Executive Officer)      
                                                      
                                                      
STEFFEN E. PALKO             Vice Chairman; President;       September 9, 1997
- -----------------------       Director                
Steffen E. Palko                                              
                                                      
                                                      
J. RICHARD SEEDS             Executive Vice President;       September 9, 1997
- -----------------------       Director                
J. Richard Seeds                                      
                                                      
                                                      
LOUIS G. BALDWIN             Senior Vice President;          September 9, 1997
- -----------------------       Chief Financial Officer;
Louis G. Baldwin              (Principal Financial    
                              Officer)                
                                                      
                                                      
BENNIE G. KNIFFEN            Senior Vice President;          September 9, 1997
- -----------------------       Controller (Principal   
Bennie G. Kniffen             Accounting Officer)     
                                                      
                                                      
J. LUTHER KING, JR.          Director                        September 9, 1997
- -----------------------                               
J. Luther King, Jr.                                   
                                                      
                                                      
JACK P. RANDALL              Director                        September 9, 1997
- -----------------------                               
Jack P. Randall                                       
                                                      
                                                      
SCOTT G. SHERMAN             Director                        September 9, 1997
- -----------------------                               
Scott G. Sherman                                      
</TABLE>

                                      -4-
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 9359}]
{"company-data": {"conformed-name": "CROSS TIMBERS OIL CO", "cik": "0000868809", "assigned-sic": "1311", "irs-number": "752347769", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "file-number": "333-35229", "film-number": "97677587"}, "business-address": {"street1": "810 HOUSTON ST", "street2": "STE 2000", "city": "FORT WORTH", "state": "TX", "zip": "76102", "phone": "8178702800"}, "mail-address": {"street1": "810 HOUSTON STREET", "street2": "STE 2000", "city": "FORT WORTH", "state": "TX", "zip": "76102"}}
As filed with the Securities and Exchange Commission on September 9, 1997

                                                 Registration No. 33-___________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549

                                   FORM S-8

            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                           CROSS TIMBERS OIL COMPANY
            (Exact name of registrant as specified in its charter)

         Delaware                                           75-2347769
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                           Identification No.)

810 Houston Street, Suite 2000, Fort Worth, Texas              76102
    (Address of Principal Executive Offices)                 (Zip Code)

              CROSS TIMBERS OIL COMPANY 1994 STOCK INCENTIVE PLAN
                           (Full title of the plan)

                              Mr. Bob R. Simpson
                        810 Houston Street, Suite 2000
                           Fort Worth, Texas  76102
                    (Name and address of agent for service)

                                (817) 870-2800
         (Telephone number, including area code, of agent for service)

                                  ----------

                                   Copy to:

                          KELLY, HART & HALLMAN, P.C.
                          201 Main Street, Suite 2500
                           Fort Worth, Texas  76102
                        Attn: F. Richard Bernasek, Esq.
Calculation of Registration Fee
================================================================================
                                           Proposed    Proposed               
                               Amount      maximum     maximum                
                                to be      offering   aggregate     Amount of 
  Title of securities        registered   price per    offering   registration
   to be registered              (1)      share (2)      price       fee (2)
- ------------------------------------------------------------------------------
Common Stock, $.01 par          300,000    $21.4375   $6,431,250     $1,948.86
 value                          shares
- ---------
(1)  Pursuant to Rule 416(a), the number of shares of Common Stock registered
     hereunder includes such indeterminate number of additional shares of Common
     Stock as may be offered or issued to prevent dilution resulting from stock
     splits, stock dividends or similar transactions.

(2)  Computed pursuant to Rules 457 (c) and (h) based on the average of the
     high and low prices on September 4, 1997.

================================================================================
PART II
              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

This Registration Statement registers additional securities to be issued under
the Cross Timbers Oil Company 1994 Stock Incentive Plan.  The contents of the
prior Registration Statement on Form S-8, Registration No. 33-81766, are hereby
incorporated by reference in this Registration Statement.

Item 8.  Exhibits.

     Exhibit Number                                                      Page
     and Description                                                    Number
     ---------------                                                    ------

     (4)   Instruments defining the rights of security holders, 
           including indentures

           4.1   Cross Timbers Oil Company 1994 Stock Incentive Plan, 
                 as amended and restated on May 21, 1996

     (5)   Opinion re legality

           5.1   Kelly, Hart & Hallman, P.C.

     (15)  Letter re unaudited interim financial information

           15.1  Awareness letter of Arthur Andersen LLP

     (23)  Consents of experts and counsel

           23.1  Consent of Arthur Andersen LLP
           23.2  Consent of Kelly, Hart & Hallman, P.C. (included in 
                 its opinion filed as Exhibit 5.1)

     (24)  Power of attorney (included on page 4 of the Registration
            Statement)

                                      -2-
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 to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Fort Worth, State of Texas, on September 9, 1997.

                                       CROSS TIMBERS OIL COMPANY

                                       By:  BOB R. SIMPSON
                                          ------------------------------
                                            Bob R. Simpson
                                            Chairman and Chief Executive Officer

                                      -3-
POWER OF ATTORNEY

     KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Bob R. Simpson and Steffen E. Palko, and each of
them, his true and lawful attorneys-in-fact and agents, with full power of
substitution and resubstitution, for him in his name, place and stead, in any
and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits hereto, and other 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, as fully to all intents
and purposes as he might or could do in person, hereby ratifying and confirming
all that said attorneys-in-fact and agents or either of them, or their or his
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 dates indicated.
Signature                      Title                          Date
     ---------                      -----                          ----
BOB R. SIMPSON               Chairman of the Board;          September 9, 1997
- -----------------------       Executive Officer;      
Bob R. Simpson                Director (Principal                        
                              Executive Officer)      
                                                      
                                                      
STEFFEN E. PALKO             Vice Chairman; President;       September 9, 1997
- -----------------------       Director                
Steffen E. Palko                                              
                                                      
                                                      
J. RICHARD SEEDS             Executive Vice President;       September 9, 1997
- -----------------------       Director                
J. Richard Seeds                                      
                                                      
                                                      
LOUIS G. BALDWIN             Senior Vice President;          September 9, 1997
- -----------------------       Chief Financial Officer;
Louis G. Baldwin              (Principal Financial    
                              Officer)                
                                                      
                                                      
BENNIE G. KNIFFEN            Senior Vice President;          September 9, 1997
- -----------------------       Controller (Principal   
Bennie G. Kniffen             Accounting Officer)     
                                                      
                                                      
J. LUTHER KING, JR.          Director                        September 9, 1997
- -----------------------                               
J. Luther King, Jr.                                   
                                                      
                                                      
JACK P. RANDALL              Director                        September 9, 1997
- -----------------------                               
Jack P. Randall                                       
                                                      
                                                      
SCOTT G. SHERMAN             Director                        September 9, 1997
- -----------------------                               
Scott G. Sherman
-4-