Exhibit 10

Execution Copy            

EXTENSION AGREEMENT

EXTENSION AGREEMENT (this “Agreement”), dated as of May 22, 2013, with respect
to the Credit Agreement, dated as of May 4, 2012 (the “Credit Agreement”), among
LYONDELLBASELL INDUSTRIES N.V., a naamloze vennootschap (a public limited
liability company) formed under the laws of The Netherlands (the “Company”), LYB
AMERICAS FINANCE COMPANY, a Delaware corporation (the “Co-Borrower” and,
together with the Company, the “Borrowers” and each, a “Borrower”), the various
institutions from time to time party to this Agreement as Lenders, BANK OF
AMERICA, N.A. (“Bank of America”), as Administrative Agent, Swing Line Lender
and L/C Issuer, DEUTSCHE BANK SECURITIES INC., as Syndication Agent, DEUTSCHE
BANK AG NEW YORK BRANCH, as L/C Issuer, MERRILL LYNCH, PIERCE, FENNER & SMITH
INCORPORATED and DEUTSCHE BANK SECURITIES INC., as Joint Lead Arrangers and
Joint Book Managers, and J.P. MORGAN SECURITIES LLC, CREDIT SUISSE SECURITIES
(USA) LLC, BARCLAYS BANK PLC, CITIBANK, N.A., HSBC SECURITIES (USA) INC., ING
BANK N.V. and WELLS FARGO SECURITIES, LLC, as Documentation Agents.

The parties hereto agree as follows:

Section 1. Defined Terms. Capitalized terms used but not defined herein shall
have the meanings given to them in the Credit Agreement.

Section 2. Extension. Each of the undersigned Lenders hereby agrees to extend
the Termination Date with respect to such Lender, pursuant to Section 2.09 of
the Credit Agreement, to May 4, 2018.

Section 3. Effectiveness. This Agreement shall become effective on and as of
May 22, 2013 (the “Extension Date”), subject only to:

(a) receipt by the Administrative Agent from the Company and from Lenders
comprising the Required Lenders of a counterpart of this Agreement signed on
behalf of such parties;

(b) the conditions precedent set forth in Section 2.09(c) of the Credit
Agreement being satisfied on and as of the Extension Date; and

(c) receipt by the Administrative Agent from the Company of payment of a fee for
the account of each undersigned Lender in the amount of 0.05% of such Lender’s
Commitment.

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Upon such effectiveness, the Termination Date shall be extended with respect to
each Lender party to this Agreement as set forth in Section 2 above. In the
event of any inconsistency between the provisions of Section 2.09 of the Credit
Agreement and the provisions of this Agreement with respect to the matters
covered hereby, the provisions of this Agreement shall prevail.

Section 4. Governing Law. This Agreement shall be construed in accordance with
and governed by the laws of the State of New York.

Section 5. Miscellaneous. This Agreement may be signed in any number of
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto and hereto were upon the same instrument. Delivery of an
executed signature page hereto by facsimile or electronic transmission (e.g.,
“pdf” or “tif”) shall be as effective as delivery of a manually executed
counterpart hereof. This Agreement shall be a Loan Document for purposes of the
Credit Agreement and other Loan Documents.

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This Agreement is entered into between us as of the date first above written.

 

LYONDELLBASELL INDUSTRIES N.V. By:   /s/ Francesco Svelto  

 

  Name: Francesco Svelto   Title: Attorney-in-Fact

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BANK OF AMERICA, N.A.,     as a Lender, as L/C Issuer, as Swing Line Lender
and as Administrative Agent By:   /s/ Edwin B. Cox, Jr.  

 

  Name: Edwin B. Cox, Jr.   Title: Managing Director

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DEUTSCHE BANK AG NEW YORK BRANCH By:   /s/ Ming K. Chu  

 

  Name: Ming K. Chu   Title: Vice President By:   /s/ Philippe Sandmeier  

 

  Name: Philippe Sandmeier   Title: Managing Director

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CITIBANK, N.A. By:   /s/ David Jaffe  

 

  Name: David Jaffe   Title: Vice President

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JPMORGAN CHANSE BANK, N.A. By:   /s/ Peter S. Predun  

 

  Name: Peter S. Predun   Title: Executive Director

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BARCLAYS BANK PLC By:   /s/ Vanessa A. Kurbatskry  

 

  Name: Vanessa A. Kurbatskry   Title: Vice President

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Credit Suisse AG, Cayman Islands Branch, as Lender By:   /s/ Alain Daoust  

 

  Name: Alain Daoust   Title: Authorized Signatory By:   /s/ Patrick Freytag  

 

  Name: Patrick Freytag   Title: Authorized Signatory

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WELLS FARGO BANK, N.A., as a Lender By:   /s/ David L Ericson  

 

  Name: David L Ericson   Title: Director

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HSBC Bank USA, National Association By:   /s/ David A. Mandell  

 

  Name: David A. Mandell   Title: Managing Director

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Morgan Stanley Bank, N.A. By:   /s/ Kelly Chin  

 

  Name: Kelly Chin   Title: Authorized Signatory

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THE BANK OF NOVA SCOTIA By:   /s/ John Frazell  

 

  Name: John Frazell   Title: Director

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Sumitomo Mitsui Banking Corporation By:   /s/ James D Weinstein  

 

  Name: James D Weinstein   Title: Managing Director

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Mizuho Corporate bank, Ltd. By:   /s/ Leon Mo  

 

  Name: Leon Mo   Title: Authorized Signatory

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THE BANK OF TOKYO-MITSUBISHI UFJ, LTD By:   /s/ Mark S Campbell  

 

  Name: Mark S Campbell   Title: Authorized Signatory

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PNC BANK, NATIONAL ASSOCIATION By:   /s/ John Berry  

 

  Name: John Berry   Title: Vice President

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REGIONS BANK By:   /s/ Dan Clubb  

 

  Name: Dan Clubb   Title: Vice President

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THE BANK OF NEW YORK MELLON By:   /s/ William M. Feathers  

 

  Name: William M. Feathers   Title: Vice President

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CADENCE BANK, N.A., as a Lender By:   /s/ Bill Bobbora  

 

  Name: Bill Bobbora   Title: Senior Vice President

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ING Bank N.V. By:   /s/ K P. Weehuizen  

 

  Name: K P. Weehuizen   Title: Managing Director By:   /s/ J.C. Stubenitsky  

 

  Name: J.C. Stubenitsky   Title: Vice President

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UniCredit Luxembourg S.A. By:   /s/ Michael Wieber  

 

  Name: Michael Wieber   Title: By:  

/s/ Manfredi Bianchi

 

Name: Manfredi Bianchi

Title: