<PAGE>

    As filed with the Securities and Exchange Commission on April 18, 2000
                                                       Registration No. 333-
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

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

                                   FORM S-8
                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

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

                                BP Amoco p.l.c.
            (Exact name of Registrant as specified in its charter)

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

<TABLE>
<S>                                        <C>
             England                              None
           (State or other jurisdiction     (I.R.S. Employer
        of incorporation or organization)  Identification No.)
</TABLE>

                                Britannic House
                               1 Finsbury Circus
                           London EC2M 7BA, England
                   (Address of Principal Executive Offices)

            ATLANTIC RICHFIELD COMPANY CAPITAL ACCUMULATION PLAN II
                   CH-TWENTY, INC. CAPITAL ACCUMULATION PLAN
      1985 ATLANTIC RICHFIELD COMPANY EXECUTIVE LONG-TERM INCENTIVE PLAN
      ATLANTIC RICHFIELD COMPANY STOCK OPTION PLAN FOR OUTSIDE DIRECTORS
                          (Full Titles of the Plans)

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

                            DANIEL B. PINKERT, ESQ.
                             BP Amoco Corporation
                200 E. Randolph Drive, Chicago, Illinois 60601
                                (312) 856-6111
 (Name, address including zip code, and telephone number, including area code,
                             of agent for service)

                                   Copy to:

                              DIANE A. WARD, ESQ.
                      Senior Counsel-Securities & Finance
                          Atlantic Richfield Company
             333 South Hope Street, Los Angeles, California 90071
                                (213) 486-2808

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

                        CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------
                                                             Proposed        Proposed
                                               Amount        Maximum          Maximum       Amount of
            Title of Securities                 to be     Offering Price     Aggregate     Registration
             to be Registered               Registered(2)  Per Share(3)  Offering Price(3)    Fee(3)
-------------------------------------------------------------------------------------------------------
<S>                                         <C>           <C>            <C>               <C>
Ordinary Shares(1)........................   152,520,000      $8.35       $1,273,542,000     $336,215
-------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------
</TABLE>

(1) In addition, pursuant to Rule 416(c) under the Securities Act of 1933,
    this registration statement also covers an indeterminate amount of
    interests to be offered or sold pursuant to certain of the employee
    benefit plans described herein.

(2) Pursuant to Rule 416(a) under the Securities Act of 1933, this
    Registration Statement also registers such indeterminate number of
    additional shares as may be issuable under the plans in connection with
    share splits, share dividends or similar transactions.

(3) Estimated solely for the purposes of calculating the registration fee.
    Such estimate has been computed in accordance with Rule 457(h) based on
    the average of the high and low quotation for Ordinary Shares of BP Amoco
    p.l.c. on the London Stock Exchange on April 17, 2000 and the noon buying
    rate for pounds sterling of (Pounds)1.00=$1.5853, as announced by the
    Federal Reserve on that date.

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
<PAGE>

                                     PART I

                     INFORMATION REQUIRED IN THE PROSPECTUS

ITEM 1. Plan Information

   All information required by Part I of Form S-8 to be contained in the
Section 10(a) prospectus is omitted from this Registration Statement in
accordance with Rule 428 under the Securities Act of 1933, as amended (the
"Securities Act"), and the Note to Part I of Form S-8.

ITEM 2. Registrant Information and Employee Plan Annual Information

   All information required by Part I of Form S-8 to be contained in the
Section 10(a) prospectus is omitted from this Registration Statement in
accordance with Rule 428 under the Securities Act and the Note to Part I of
Form S-8.

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. Incorporation of Certain Documents By Reference.

   The reports listed below have been filed with or furnished to the Securities
Exchange Commission (the "Commission") by BP Amoco p.l.c., formerly The British
Petroleum Company p.l.c. ("BP Amoco"), and are incorporated herein by reference
to the extent not superseded by documents or reports subsequently filed or
furnished:

    . BP Amoco's Annual Report on Form 20-F for the year ended December 31,
      1999.

    . BP Amoco's Report on Form 6-K dated March 27, 2000.

   In addition, all filings on Form 20-F filed by BP Amoco pursuant to the
Securities Exchange Act of 1934 and, to the extent designated therein, Reports
on Form 6-K filed by BP Amoco, after the date of this Registration Statement
and prior to the termination of the distribution contemplated hereby are
incorporated by reference in this Registration Statement from the date of
filing or furnishing such documents or reports.

   The following report has been filed with or furnished to the Commission by
the following plan, and is incorporated herein by reference to the extent not
superseded by documents or reports subsequently filed or furnished: The Annual
Report on Form 11-K of the Atlantic Richfield Capital Accumulation Plan II (the
"ARCO Plan") for the transition period July 1, 1998 to March 14, 1999.

ITEM 4. Description of Securities.

   Not applicable.

ITEM 5. Interests of Named Experts and Counsel.

   The validity of the Ordinary Shares registered herein has been passed upon
by Peter B.P. Bevan, Group General Counsel of BP Amoco. The validity of the
plan interests in the ARCO Plan and the CH-Twenty, Inc. Capital Accumulation
Plan sponsored by ARCO (collectively with the ARCO Plan, the "ARCO Plans") have
been passed upon by Diane A. Ward, Senior Counsel--Securities & Finance,
Atlantic Richfield Company.

                                      II-1
<PAGE>

ITEM 6. Indemnification of Directors and Officers.

   Article 137 of BP Amoco's Articles of Association provides:

   "Subject to the provisions of and so far as may be consistent with the
Statutes, every Director, Auditor, Secretary or other officer of the Company
shall be entitled to be indemnified by the Company against all costs, charges,
losses, expenses and liabilities incurred by him in the execution and/or
discharge of his duties and/or the exercise of his powers and/or otherwise in
relation to or in connection with his duties, powers or office."

   Section 310 of the Companies Act 1985 (as amended by Section 137 of the
Companies Act 1989) provides as follows:

   "310--Provisions exempting officers and auditors from liability.

   (1) This section applies to any provision, whether contained in a company's
articles or in any contract with the company or otherwise, for exempting any
officer of the company or any person (whether an officer or not) employed by
the company as auditor from, or indemnifying him against, any liability which
by virtue of any rule of law would otherwise attach to him in respect of any
negligence, default, breach of duty or breach of trust of which he may be
guilty in relation to the company.

   (2) Except as provided by the following subsection, any such provision is
void.

   (3) This section does not prevent a company

     (a) from purchasing and maintaining for any such officer or auditor
  insurance against any such liability, or

     (b) from indemnifying any such officer or auditor against any liability
  incurred by him -

       (i) in defending any proceedings (whether civil or criminal) in
    which judgment is given in his favor or he is acquitted, or

       (ii) in connection with any application under section 144(3) or (4)
    (acquisition of shares by innocent nominee) or Section 727 (general
    power to grant relief in case of honest and reasonable conduct) in
    which relief is granted to him by the court."

   Section 727 of the Companies Act 1985 of the United Kingdom provides as
follows:

   "727--Power of court to grant relief in certain circumstances:

   (1)  If in any proceedings for negligence, default, breach of duty or breach
of trust against an officer of a company or a person employed by a company as
auditor (whether he is or is not an officer of the company) it appears to the
court hearing the case that that officer or person is or may be liable in
respect of the negligence, default, breach of duty or breach of trust, but that
he has acted honestly and reasonably, and that having regard to all the
circumstances of the case (including those connected with his appointment) he
ought fairly to be excused for the negligence, default, breach of duty or
breach of trust, that court may relieve him, either wholly or partly, from his
liability on such terms as it thinks fit.

   (2)  If any such officer or person as above-mentioned has reason to
apprehend that any claim will or might be made against him in respect of any
negligence, default, breach of duty or breach of trust, he may apply to the
court for relief; and the court on the application has the same power to
relieve him as under this section it would have had if it had been a court
before which proceedings against that person for negligence, default, breach of
duty or breach of trust had been brought.

   (3)  Where a case to which subsection (1) applies is being tried by a judge
with a jury, the judge, after hearing the evidence, may, if he is satisfied
that the defendant or defender ought in pursuance of that subsection to be
relieved either in whole or in part from the liability sought to be enforced
against him, withdraw the case

                                      II-2
<PAGE>

in whole or in part from the jury and forthwith direct judgment to be entered
for the defendant or defender on such terms as to costs or otherwise as the
judge may think proper."

   BP Amoco maintains directors' and officers' liability insurance for its
directors and officers.

ITEM 7. Exemption from Registration Claimed.

   Not applicable.

ITEM 8. Exhibits.

   See the Exhibit Index which is incorporated herein by reference. The
Registrant hereby undertakes that it will submit, or has submitted, the ARCO
Plans and any amendments thereto to the Internal Revenue Service ("IRS"), and
has made or will make all changes required by the IRS in order to qualify the
ARCO Plans.

ITEM 9. Undertakings.

   The undersigned Registrant hereby undertakes:

   (1) To file, during any period in which offers or sales are being made, a
post-effective amendment to this registration statement: (i) to include any
prospectus required by section 10(a)(3) of the Securities Act of 1933; (ii) to
reflect in the prospectus any facts or events arising after the effective date
of the registration statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate, represent a fundamental
change in the information set forth in the registration statement.
Notwithstanding the foregoing, any increase or decrease in volume of securities
offered (if the total dollar value of securities offered would not exceed that
which was required) and any deviation from the low or high end of the estimated
maximum offering range may be reflected in the form of prospectus filed with
the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in
volume and price represent no more than 20 percent change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective registration statement; (iii) to include any material
information with respect to the plan of distribution not previously disclosed
in the registration statement or any material change to such information in the
registration statement, provided however, that paragraphs (a)(1)(i) and
(a)(1)(ii) do not apply if the registration statement is on Form S-3, Form S-8
or Form F-3, and the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed with or
furnished to the Commission by the registrant pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934 that are incorporated by references in
the registration statement.

   (2) That, for the purpose of determining any liability under the Securities
Act of 1933, each such post- effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

   (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of
the offering.

   The undersigned Registrant hereby undertakes that, for purpose of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report on Form 20-F pursuant to Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 (and each filing of each of the
Savings Plans annual reports on Form 11-K pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

                                      II-3
<PAGE>

   Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the provisions set forth in Item 6, or otherwise, the
Registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.

                                      II-4
<PAGE>

                          SIGNATURE OF BP AMOCO P.L.C.

   Pursuant to the requirements of the Securities Act of 1933, BP Amoco p.l.c.
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 London, England, on the 17th day of April, 2000.

                                          BP AMOCO p.l.c.

                                                 /s/ Judith C. Hanratty
                                          By: _________________________________
                                                     Name: Judith C. Hanratty
                                                     Title:  Company Secretary

   KNOW ALL MEN BY THESE PRESENTS that each person whose signature appears
below constitutes and appoints Robert D. Agdern and Daniel B. Pinkert, his or
her true and lawful attorneys-in-fact, each with power of substitution, in his
or 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 to file the same with all exhibits thereto, and all other
documents in connection therewith, with the Securities and Exchange Commission,
granting unto the 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 or she might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or their
or his or 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
indicated capacities on the 17th day of April, 2000.

<TABLE>
<CAPTION>
             Signature                                 Title
             ---------                                 -----
<S>                                  <C>
      /s/ P. D. Sutherland           Non-Executive Chairman
____________________________________
          P. D. Sutherland

      /s/ Sir Ian Prosser            Non-Executive Deputy Chairman
____________________________________
          Sir Ian Prosser

      /s/ Sir John Browne            Executive Director and Group Chief
____________________________________  Executive (Principal Executive Officer)
          Sir John Browne

   /s/ Dr. J. G. S. Buchanan         Executive Director and Chief Financial
____________________________________  Officer (Principal Financial and
       Dr. J. G. S. Buchanan          Accounting Officer)


        /s/ Rodney Chase             Executive Director and Deputy Chief
____________________________________  Executive Officer
            Rodney Chase


       /s/ W. Douglas Ford           Executive Director
____________________________________
          W. Douglas Ford
</TABLE>

                                      II-5
<PAGE>

<TABLE>
<CAPTION>
             Signature                                 Title
             ---------                                 -----
<S>                                  <C>
   /s/ Dr. C.S. Gibson-Smith         Executive Director
____________________________________
       Dr. C. S. Gibson-Smith

        /s/ R. L. Olver              Executive Director
____________________________________
            R. L. Olver

      /s/ B. K. Sanderson            Executive Director
____________________________________
          B. K. Sanderson

        /s/ R. S. Block              Non-Executive Director
____________________________________
            R. S. Block

        /s/ J. H. Bryan              Non-Executive Director
____________________________________
            J. H. Bryan

      /s/ E. B. Davis, Jr.           Non-Executive Director
____________________________________
          E. B. Davis, Jr.

        /s/ R. J. Ferris             Non-Executive Director
____________________________________
            R. J. Ferris

        /s/ C. F. Knight             Non-Executive Director
____________________________________
            C. F. Knight

       /s/ F. A. Maljers             Non-Executive Director
____________________________________
           F. A. Maljers

      /s/ Dr. W. E. Massey           Non-Executive Director
____________________________________
          Dr. W. E. Massey

       /s/ H. M. P. Miles            Non-Executive Director
____________________________________
           H. M. P. Miles

    /s/ Sir Robin Nicholson          Non-Executive Director
____________________________________
        Sir Robin Nicholson

        /s/ M. H. Wilson             Non-Executive Director
____________________________________
            M. H. Wilson

    /s/ Sir Robert P. Wilson         Non-Executive Director
____________________________________
        Sir Robert P. Wilson

/s/ The Lord Wright of Richmond      Non-Executive Director
____________________________________
    The Lord Wright of Richmond

     /s/ Daniel B. Pinkert           Authorized Representative in the United
____________________________________  States
         Daniel B. Pinkert
</TABLE>

                                      II-6
<PAGE>

    SIGNATURE OF THE ATLANTIC RICHFIELD COMPANY CAPITAL ACCUMULATION PLAN II

   Pursuant to the requirements of the Securities Act of 1933, the plan
administrator has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Los
Angeles, State of California, on April 17, 2000.

                                          ATLANTIC RICHFIELD COMPANY CAPITAL
                                          ACCUMULATION PLAN II

                                          By: Atlantic Richfield Company
                                              Capital Accumulation Plan II
                                              Secretary of the Administrative
                                              Committee

                                               /s/ Cynthia L. Bengtson
                                          By: _________________________________
                                                    Cynthia L. Bengtson

                                      II-7
<PAGE>

           SIGNATURE OF THE CH-TWENTY, INC. CAPITAL ACCUMULATION PLAN

   Pursuant to the requirement of the Securities Act of 1933, the plan
administrator has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Los
Angeles, State of California, on April 17, 2000.


                                          By: CH-Twenty, Inc. Capital
                                              Accumulation Plan
                                              Secretary to the Administration
                                              Committee

                                          By:   /s/ Cynthia L. Bengtson
                                             _______________________________
                                                   Cynthia L. Bengston

                                      II-8
<PAGE>

                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
 Exhibit
   No.                                 Description
 -------                               -----------

 <C>     <S>
 4.1     Memorandum and Articles of Association of BP Amoco as amended to date,
         incorporated by reference to BP Amoco's report on Form 20-F for the
         year ended December 31, 1999.

 4.2     Amended and Restated Deposit Agreement dated as of December 31, 1998
         to Deposit Agreement dated as of February 1, 1970, among BP Amoco
         p.l.c., Amoco Corporation, Morgan Guaranty Trust Company of New York
         and all holders from time to time of American Depositary Receipts
         issued thereunder, including the form of American Depositary Receipts,
         incorporated by reference to Exhibit (a)(2) to the Registration
         Statement on Form F-6 (No. 333-10928).

 4.3(a)  Amended and Restated Atlantic Richfield Company Capital Accumulation
         Plan (the "CAP Plan"), effective March 15, 1999, incorporated by
         reference to Exhibit 10.1 to Atlantic Richfield Company's Report on
         Form 10-Q for the period ended September 30, 1999, under File No. 1-
         1196.

 4.3(b)  CAP Plan II Trust Agreement between the Company and State Street Bank
         and Trust Company, as Trustee for the CAP Plan II (the "Trustee"),
         effective July 1, 1988, filed as exhibit to the Registration Statement
         on Form S-8 of Atlantic Richfield Company (No. 333-26901).

 4.3(c)  Amendment No. 1 to the Cap Plan II Trust Agreement between Atlantic
         Richfield Company and the Trustee for the CAP Plan II, effective
         August 5, 1996, incorporated by reference to Exhibit [  ] to
         Registration Statement on Form S-8 of Atlantic Richfield Company (No.
         333-26901) filed May 12, 1997.

 4.4     Amended and Restated CH-Twenty, Inc. Capital Accumulation Plan,
         incorporated by reference to Exhibit 10.2 to Atlantic Richfield
         Company's Report on Form 10-Q for the period ended September 30, 1999,
         under File No. 1-1196.

 4.5(a)  Atlantic Richfield Company's 1985 Executive Long-Term Incentive Plan,
         as adopted by the Board of Directors of ARCO on May 28, 1985, and
         effective as of that date, as amended through July 28, 1997,
         incorporated by reference to Exhibit 10.6 to Atlantic Richfield
         Company's Report on Form 10-K for the year 1997, under File No. 1-
         1196.

 4.5(b)  Amendment No. 10 to the Atlantic Richfield Company 1985 Executive
         Long-Term Incentive Plan, effective as of July 18, 1997, incorporated
         by reference to Exhibit 10.5 to Atlantic Richfield Company's Report on
         Form 10-Q for the quarterly period ended September 30, 1998, under
         File No. 1-1196.

 4.5(c)  Amendment No. 11 to the Atlantic Richfield Company 1985 Executive
         Long-Term Incentive Plan, effective as of July 18, 1997, incorporated
         by reference to Exhibit 10.6 to Atlantic Richfield Company's Report on
         Form 10-Q for the quarterly period ended September 30, 1998, under
         File No. 1-1196.

 4.5(d)  Amendment No. 12 to Atlantic Richfield Company 1985 Executive Long-
         Term Incentive Plan, effective March 23, 1999, incorporated by
         reference to Exhibit 10.3 to Atlantic Richfield Company's Report on
         Form 10-Q for the period ended September 30, 1999, under File No. 1-
         1196.

 4.5(e)  Amendment No. 13 to Atlantic Richfield Company 1985 Executive Long-
         Term Incentive Plan, effective March 31, 1999, incorporated by
         reference to Exhibit 10.4 to Atlantic Richfield Company's Report on
         Form 10-Q for the period ended September 30, 1999, under File No. 1-
         1196.
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
 Exhibit
   No.                                 Description
 -------                               -----------

 <C>     <S>
 4.6(a)  Stock Option Plan for Outside Directors effective as of December 17,
         1990, incorporated by reference to Exhibit 10.14 to Atlantic Richfield
         Company's report on Form 10-K for the year 1990, under File No. 1-
         1196.

 4.6(b)  Amendment No. 1 to the Stock Option Plan for Outside Directors,
         effective as of June 22, 1992, incorporated by reference to Exhibit
         10.13(b) to Atlantic Richfield Company's report on Form 10-K for the
         year 1992, under File No. 1-1196.

 4.6(c)  Amendment No. 2 to the Stock Option Plan for Outside Directors amended
         effective as of April 1, 1997, incorporated by reference to Exhibit
         10.10(c) to Atlantic Richfield Company's report on Form 10-K for the
         year 1997, under File No. 1-1196.

 4.6(d)  Amendment No. 3 to the Stock Option Plan for Outside Directors amended
         effective as of April 1, 1997, incorporated by reference to Exhibit
         10.10(d) to Atlantic Richfield Company's report on Form 10-K for the
         year 1997, under File No. 1-1196.

 5.1     Opinion of Peter B.P. Bevan, General Counsel of BP Amoco, as to the
         validity of the Ordinary Shares being registered.

 5.2     Opinion of Diane A. Ward, Senior Counsel--Securities & Finance of
         Atlantic Richfield Company, as to the validity of the plan interests
         being registered.

 23.1    Consent of Ernst & Young, independent auditors, London, England.

 23.2    Consent of PricewaterhouseCoopers LLP, independent accountants,
         Chicago, Illinois.

 23.3    Consent of PricewaterhouseCoopers LLP, independent accountants, Los
         Angeles, California.

 23.4    Consent of Peter B.P. Bevan, General Counsel of BP Amoco (included in
         Exhibit 5).

 23.5    Consent of Diane A. Ward, Senior Counsel of Atlantic Richfield Company
         (included in Exhibit 5).

 24      Powers of Attorney (included on the signature page hereof).
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 29514}]
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As filed with the Securities and Exchange Commission on April 18, 2000
                                                       Registration No. 333-
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

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

                                   FORM S-8
                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

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

                                BP Amoco p.l.c.
            (Exact name of Registrant as specified in its charter)

                                ---------------
England                              None
           (State or other jurisdiction     (I.R.S. Employer
        of incorporation or organization)  Identification No.)
Britannic House
                               1 Finsbury Circus
                           London EC2M 7BA, England
                   (Address of Principal Executive Offices)

            ATLANTIC RICHFIELD COMPANY CAPITAL ACCUMULATION PLAN II
                   CH-TWENTY, INC. CAPITAL ACCUMULATION PLAN
      1985 ATLANTIC RICHFIELD COMPANY EXECUTIVE LONG-TERM INCENTIVE PLAN
      ATLANTIC RICHFIELD COMPANY STOCK OPTION PLAN FOR OUTSIDE DIRECTORS
                          (Full Titles of the Plans)

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

                            DANIEL B. PINKERT, ESQ.
                             BP Amoco Corporation
                200 E. Randolph Drive, Chicago, Illinois 60601
                                (312) 856-6111
 (Name, address including zip code, and telephone number, including area code,
                             of agent for service)

                                   Copy to:

                              DIANE A. WARD, ESQ.
                      Senior Counsel-Securities & Finance
                          Atlantic Richfield Company
             333 South Hope Street, Los Angeles, California 90071
                                (213) 486-2808

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

                        CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------
                                                             Proposed        Proposed
                                               Amount        Maximum          Maximum       Amount of
            Title of Securities                 to be     Offering Price     Aggregate     Registration
             to be Registered               Registered(2)  Per Share(3)  Offering Price(3)    Fee(3)
-------------------------------------------------------------------------------------------------------
Ordinary Shares(1)........................   152,520,000      $8.35       $1,273,542,000     $336,215
-------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------
(1) In addition, pursuant to Rule 416(c) under the Securities Act of 1933,
    this registration statement also covers an indeterminate amount of
    interests to be offered or sold pursuant to certain of the employee
    benefit plans described herein.

(2) Pursuant to Rule 416(a) under the Securities Act of 1933, this
    Registration Statement also registers such indeterminate number of
    additional shares as may be issuable under the plans in connection with
    share splits, share dividends or similar transactions.

(3) Estimated solely for the purposes of calculating the registration fee.
    Such estimate has been computed in accordance with Rule 457(h) based on
    the average of the high and low quotation for Ordinary Shares of BP Amoco
    p.l.c. on the London Stock Exchange on April 17, 2000 and the noon buying
    rate for pounds sterling of (Pounds)1.00=$1.5853, as announced by the
    Federal Reserve on that date.

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
PART I

                     INFORMATION REQUIRED IN THE PROSPECTUS

ITEM 1. Plan Information

   All information required by Part I of Form S-8 to be contained in the
Section 10(a) prospectus is omitted from this Registration Statement in
accordance with Rule 428 under the Securities Act of 1933, as amended (the
"Securities Act"), and the Note to Part I of Form S-8.

ITEM 2. Registrant Information and Employee Plan Annual Information

   All information required by Part I of Form S-8 to be contained in the
Section 10(a) prospectus is omitted from this Registration Statement in
accordance with Rule 428 under the Securities Act and the Note to Part I of
Form S-8.

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. Incorporation of Certain Documents By Reference.

   The reports listed below have been filed with or furnished to the Securities
Exchange Commission (the "Commission") by BP Amoco p.l.c., formerly The British
Petroleum Company p.l.c. ("BP Amoco"), and are incorporated herein by reference
to the extent not superseded by documents or reports subsequently filed or
furnished:

    . BP Amoco's Annual Report on Form 20-F for the year ended December 31,
      1999.

    . BP Amoco's Report on Form 6-K dated March 27, 2000.

   In addition, all filings on Form 20-F filed by BP Amoco pursuant to the
Securities Exchange Act of 1934 and, to the extent designated therein, Reports
on Form 6-K filed by BP Amoco, after the date of this Registration Statement
and prior to the termination of the distribution contemplated hereby are
incorporated by reference in this Registration Statement from the date of
filing or furnishing such documents or reports.

   The following report has been filed with or furnished to the Commission by
the following plan, and is incorporated herein by reference to the extent not
superseded by documents or reports subsequently filed or furnished: The Annual
Report on Form 11-K of the Atlantic Richfield Capital Accumulation Plan II (the
"ARCO Plan") for the transition period July 1, 1998 to March 14, 1999.

ITEM 4. Description of Securities.

   Not applicable.

ITEM 5. Interests of Named Experts and Counsel.

   The validity of the Ordinary Shares registered herein has been passed upon
by Peter B.P. Bevan, Group General Counsel of BP Amoco. The validity of the
plan interests in the ARCO Plan and the CH-Twenty, Inc. Capital Accumulation
Plan sponsored by ARCO (collectively with the ARCO Plan, the "ARCO Plans") have
been passed upon by Diane A. Ward, Senior Counsel--Securities & Finance,
Atlantic Richfield Company.

                                      II-1
ITEM 6. Indemnification of Directors and Officers.

   Article 137 of BP Amoco's Articles of Association provides:

   "Subject to the provisions of and so far as may be consistent with the
Statutes, every Director, Auditor, Secretary or other officer of the Company
shall be entitled to be indemnified by the Company against all costs, charges,
losses, expenses and liabilities incurred by him in the execution and/or
discharge of his duties and/or the exercise of his powers and/or otherwise in
relation to or in connection with his duties, powers or office."

   Section 310 of the Companies Act 1985 (as amended by Section 137 of the
Companies Act 1989) provides as follows:

   "310--Provisions exempting officers and auditors from liability.

   (1) This section applies to any provision, whether contained in a company's
articles or in any contract with the company or otherwise, for exempting any
officer of the company or any person (whether an officer or not) employed by
the company as auditor from, or indemnifying him against, any liability which
by virtue of any rule of law would otherwise attach to him in respect of any
negligence, default, breach of duty or breach of trust of which he may be
guilty in relation to the company.

   (2) Except as provided by the following subsection, any such provision is
void.

   (3) This section does not prevent a company

     (a) from purchasing and maintaining for any such officer or auditor
  insurance against any such liability, or

     (b) from indemnifying any such officer or auditor against any liability
  incurred by him -

       (i) in defending any proceedings (whether civil or criminal) in
    which judgment is given in his favor or he is acquitted, or

       (ii) in connection with any application under section 144(3) or (4)
    (acquisition of shares by innocent nominee) or Section 727 (general
    power to grant relief in case of honest and reasonable conduct) in
    which relief is granted to him by the court."

   Section 727 of the Companies Act 1985 of the United Kingdom provides as
follows:

   "727--Power of court to grant relief in certain circumstances:

   (1)  If in any proceedings for negligence, default, breach of duty or breach
of trust against an officer of a company or a person employed by a company as
auditor (whether he is or is not an officer of the company) it appears to the
court hearing the case that that officer or person is or may be liable in
respect of the negligence, default, breach of duty or breach of trust, but that
he has acted honestly and reasonably, and that having regard to all the
circumstances of the case (including those connected with his appointment) he
ought fairly to be excused for the negligence, default, breach of duty or
breach of trust, that court may relieve him, either wholly or partly, from his
liability on such terms as it thinks fit.

   (2)  If any such officer or person as above-mentioned has reason to
apprehend that any claim will or might be made against him in respect of any
negligence, default, breach of duty or breach of trust, he may apply to the
court for relief; and the court on the application has the same power to
relieve him as under this section it would have had if it had been a court
before which proceedings against that person for negligence, default, breach of
duty or breach of trust had been brought.

   (3)  Where a case to which subsection (1) applies is being tried by a judge
with a jury, the judge, after hearing the evidence, may, if he is satisfied
that the defendant or defender ought in pursuance of that subsection to be
relieved either in whole or in part from the liability sought to be enforced
against him, withdraw the case

                                      II-2
in whole or in part from the jury and forthwith direct judgment to be entered
for the defendant or defender on such terms as to costs or otherwise as the
judge may think proper."

   BP Amoco maintains directors' and officers' liability insurance for its
directors and officers.

ITEM 7. Exemption from Registration Claimed.

   Not applicable.

ITEM 8. Exhibits.

   See the Exhibit Index which is incorporated herein by reference. The
Registrant hereby undertakes that it will submit, or has submitted, the ARCO
Plans and any amendments thereto to the Internal Revenue Service ("IRS"), and
has made or will make all changes required by the IRS in order to qualify the
ARCO Plans.

ITEM 9. Undertakings.

   The undersigned Registrant hereby undertakes:

   (1) To file, during any period in which offers or sales are being made, a
post-effective amendment to this registration statement: (i) to include any
prospectus required by section 10(a)(3) of the Securities Act of 1933; (ii) to
reflect in the prospectus any facts or events arising after the effective date
of the registration statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate, represent a fundamental
change in the information set forth in the registration statement.
Notwithstanding the foregoing, any increase or decrease in volume of securities
offered (if the total dollar value of securities offered would not exceed that
which was required) and any deviation from the low or high end of the estimated
maximum offering range may be reflected in the form of prospectus filed with
the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in
volume and price represent no more than 20 percent change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective registration statement; (iii) to include any material
information with respect to the plan of distribution not previously disclosed
in the registration statement or any material change to such information in the
registration statement, provided however, that paragraphs (a)(1)(i) and
(a)(1)(ii) do not apply if the registration statement is on Form S-3, Form S-8
or Form F-3, and the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed with or
furnished to the Commission by the registrant pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934 that are incorporated by references in
the registration statement.

   (2) That, for the purpose of determining any liability under the Securities
Act of 1933, each such post- effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

   (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of
the offering.

   The undersigned Registrant hereby undertakes that, for purpose of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report on Form 20-F pursuant to Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 (and each filing of each of the
Savings Plans annual reports on Form 11-K pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

                                      II-3
Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the provisions set forth in Item 6, or otherwise, the
Registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.

                                      II-4
SIGNATURE OF BP AMOCO P.L.C.

   Pursuant to the requirements of the Securities Act of 1933, BP Amoco p.l.c.
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 London, England, on the 17th day of April, 2000.

                                          BP AMOCO p.l.c.

                                                 /s/ Judith C. Hanratty
                                          By: _________________________________
                                                     Name: Judith C. Hanratty
                                                     Title:  Company Secretary

   KNOW ALL MEN BY THESE PRESENTS that each person whose signature appears
below constitutes and appoints Robert D. Agdern and Daniel B. Pinkert, his or
her true and lawful attorneys-in-fact, each with power of substitution, in his
or 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 to file the same with all exhibits thereto, and all other
documents in connection therewith, with the Securities and Exchange Commission,
granting unto the 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 or she might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or their
or his or 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
indicated capacities on the 17th day of April, 2000.
Signature                                 Title
             ---------                                 -----
/s/ P. D. Sutherland           Non-Executive Chairman
____________________________________
          P. D. Sutherland

      /s/ Sir Ian Prosser            Non-Executive Deputy Chairman
____________________________________
          Sir Ian Prosser

      /s/ Sir John Browne            Executive Director and Group Chief
____________________________________  Executive (Principal Executive Officer)
          Sir John Browne

   /s/ Dr. J. G. S. Buchanan         Executive Director and Chief Financial
____________________________________  Officer (Principal Financial and
       Dr. J. G. S. Buchanan          Accounting Officer)

        /s/ Rodney Chase             Executive Director and Deputy Chief
____________________________________  Executive Officer
            Rodney Chase

       /s/ W. Douglas Ford           Executive Director
____________________________________
          W. Douglas Ford
II-5
Signature                                 Title
             ---------                                 -----
/s/ Dr. C.S. Gibson-Smith         Executive Director
____________________________________
       Dr. C. S. Gibson-Smith

        /s/ R. L. Olver              Executive Director
____________________________________
            R. L. Olver

      /s/ B. K. Sanderson            Executive Director
____________________________________
          B. K. Sanderson

        /s/ R. S. Block              Non-Executive Director
____________________________________
            R. S. Block

        /s/ J. H. Bryan              Non-Executive Director
____________________________________
            J. H. Bryan

      /s/ E. B. Davis, Jr.           Non-Executive Director
____________________________________
          E. B. Davis, Jr.

        /s/ R. J. Ferris             Non-Executive Director
____________________________________
            R. J. Ferris

        /s/ C. F. Knight             Non-Executive Director
____________________________________
            C. F. Knight

       /s/ F. A. Maljers             Non-Executive Director
____________________________________
           F. A. Maljers

      /s/ Dr. W. E. Massey           Non-Executive Director
____________________________________
          Dr. W. E. Massey

       /s/ H. M. P. Miles            Non-Executive Director
____________________________________
           H. M. P. Miles

    /s/ Sir Robin Nicholson          Non-Executive Director
____________________________________
        Sir Robin Nicholson

        /s/ M. H. Wilson             Non-Executive Director
____________________________________
            M. H. Wilson

    /s/ Sir Robert P. Wilson         Non-Executive Director
____________________________________
        Sir Robert P. Wilson

/s/ The Lord Wright of Richmond      Non-Executive Director
____________________________________
    The Lord Wright of Richmond

     /s/ Daniel B. Pinkert           Authorized Representative in the United
____________________________________  States
         Daniel B. Pinkert
II-6
SIGNATURE OF THE ATLANTIC RICHFIELD COMPANY CAPITAL ACCUMULATION PLAN II

   Pursuant to the requirements of the Securities Act of 1933, the plan
administrator has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Los
Angeles, State of California, on April 17, 2000.

                                          ATLANTIC RICHFIELD COMPANY CAPITAL
                                          ACCUMULATION PLAN II

                                          By: Atlantic Richfield Company
                                              Capital Accumulation Plan II
                                              Secretary of the Administrative
                                              Committee

                                               /s/ Cynthia L. Bengtson
                                          By: _________________________________
                                                    Cynthia L. Bengtson

                                      II-7
SIGNATURE OF THE CH-TWENTY, INC. CAPITAL ACCUMULATION PLAN

   Pursuant to the requirement of the Securities Act of 1933, the plan
administrator has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Los
Angeles, State of California, on April 17, 2000.

                                          By: CH-Twenty, Inc. Capital
                                              Accumulation Plan
                                              Secretary to the Administration
                                              Committee

                                          By:   /s/ Cynthia L. Bengtson
                                             _______________________________
                                                   Cynthia L. Bengston

                                      II-8
EXHIBIT INDEX
Exhibit
   No.                                 Description
 -------                               -----------
4.1     Memorandum and Articles of Association of BP Amoco as amended to date,
         incorporated by reference to BP Amoco's report on Form 20-F for the
         year ended December 31, 1999.

 4.2     Amended and Restated Deposit Agreement dated as of December 31, 1998
         to Deposit Agreement dated as of February 1, 1970, among BP Amoco
         p.l.c., Amoco Corporation, Morgan Guaranty Trust Company of New York
         and all holders from time to time of American Depositary Receipts
         issued thereunder, including the form of American Depositary Receipts,
         incorporated by reference to Exhibit (a)(2) to the Registration
         Statement on Form F-6 (No. 333-10928).

 4.3(a)  Amended and Restated Atlantic Richfield Company Capital Accumulation
         Plan (the "CAP Plan"), effective March 15, 1999, incorporated by
         reference to Exhibit 10.1 to Atlantic Richfield Company's Report on
         Form 10-Q for the period ended September 30, 1999, under File No. 1-
         1196.

 4.3(b)  CAP Plan II Trust Agreement between the Company and State Street Bank
         and Trust Company, as Trustee for the CAP Plan II (the "Trustee"),
         effective July 1, 1988, filed as exhibit to the Registration Statement
         on Form S-8 of Atlantic Richfield Company (No. 333-26901).

 4.3(c)  Amendment No. 1 to the Cap Plan II Trust Agreement between Atlantic
         Richfield Company and the Trustee for the CAP Plan II, effective
         August 5, 1996, incorporated by reference to Exhibit [  ] to
         Registration Statement on Form S-8 of Atlantic Richfield Company (No.
         333-26901) filed May 12, 1997.

 4.4     Amended and Restated CH-Twenty, Inc. Capital Accumulation Plan,
         incorporated by reference to Exhibit 10.2 to Atlantic Richfield
         Company's Report on Form 10-Q for the period ended September 30, 1999,
         under File No. 1-1196.

 4.5(a)  Atlantic Richfield Company's 1985 Executive Long-Term Incentive Plan,
         as adopted by the Board of Directors of ARCO on May 28, 1985, and
         effective as of that date, as amended through July 28, 1997,
         incorporated by reference to Exhibit 10.6 to Atlantic Richfield
         Company's Report on Form 10-K for the year 1997, under File No. 1-
         1196.

 4.5(b)  Amendment No. 10 to the Atlantic Richfield Company 1985 Executive
         Long-Term Incentive Plan, effective as of July 18, 1997, incorporated
         by reference to Exhibit 10.5 to Atlantic Richfield Company's Report on
         Form 10-Q for the quarterly period ended September 30, 1998, under
         File No. 1-1196.

 4.5(c)  Amendment No. 11 to the Atlantic Richfield Company 1985 Executive
         Long-Term Incentive Plan, effective as of July 18, 1997, incorporated
         by reference to Exhibit 10.6 to Atlantic Richfield Company's Report on
         Form 10-Q for the quarterly period ended September 30, 1998, under
         File No. 1-1196.

 4.5(d)  Amendment No. 12 to Atlantic Richfield Company 1985 Executive Long-
         Term Incentive Plan, effective March 23, 1999, incorporated by
         reference to Exhibit 10.3 to Atlantic Richfield Company's Report on
         Form 10-Q for the period ended September 30, 1999, under File No. 1-
         1196.

 4.5(e)  Amendment No. 13 to Atlantic Richfield Company 1985 Executive Long-
         Term Incentive Plan, effective March 31, 1999, incorporated by
         reference to Exhibit 10.4 to Atlantic Richfield Company's Report on
         Form 10-Q for the period ended September 30, 1999, under File No. 1-
         1196.
Exhibit
   No.                                 Description
 -------                               -----------
4.6(a)  Stock Option Plan for Outside Directors effective as of December 17,
         1990, incorporated by reference to Exhibit 10.14 to Atlantic Richfield
         Company's report on Form 10-K for the year 1990, under File No. 1-
         1196.

 4.6(b)  Amendment No. 1 to the Stock Option Plan for Outside Directors,
         effective as of June 22, 1992, incorporated by reference to Exhibit
         10.13(b) to Atlantic Richfield Company's report on Form 10-K for the
         year 1992, under File No. 1-1196.

 4.6(c)  Amendment No. 2 to the Stock Option Plan for Outside Directors amended
         effective as of April 1, 1997, incorporated by reference to Exhibit
         10.10(c) to Atlantic Richfield Company's report on Form 10-K for the
         year 1997, under File No. 1-1196.

 4.6(d)  Amendment No. 3 to the Stock Option Plan for Outside Directors amended
         effective as of April 1, 1997, incorporated by reference to Exhibit
         10.10(d) to Atlantic Richfield Company's report on Form 10-K for the
         year 1997, under File No. 1-1196.

 5.1     Opinion of Peter B.P. Bevan, General Counsel of BP Amoco, as to the
         validity of the Ordinary Shares being registered.

 5.2     Opinion of Diane A. Ward, Senior Counsel--Securities & Finance of
         Atlantic Richfield Company, as to the validity of the plan interests
         being registered.

 23.1    Consent of Ernst & Young, independent auditors, London, England.

 23.2    Consent of PricewaterhouseCoopers LLP, independent accountants,
         Chicago, Illinois.

 23.3    Consent of PricewaterhouseCoopers LLP, independent accountants, Los
         Angeles, California.

 23.4    Consent of Peter B.P. Bevan, General Counsel of BP Amoco (included in
         Exhibit 5).

 23.5    Consent of Diane A. Ward, Senior Counsel of Atlantic Richfield Company
         (included in Exhibit 5).

 24      Powers of Attorney (included on the signature page hereof).