Exhibit 10

ACCESSION AGREEMENT

ACCESSION AGREEMENT dated as of July 28, 2008 (“this Agreement”) among US BANK,
NATIONAL ASSOCIATION, SOCIETE GENERALE, and THE GOVERNOR AND COMPANY OF THE BANK
OF IRELAND (each, an “Acceding Lender”, and collectively, the “Acceding
Lenders”), ALCOA INC., a Pennsylvania corporation (“Alcoa”), and CITIBANK, N.A.,
as administrative agent (the “Administrative Agent”) for the Lenders and Issuers
(as defined in the Credit Agreement referred to below).

A. Reference is made to the Five-Year Revolving Credit Agreement dated as of
October 2, 2007 (as amended from time to time, the “Credit Agreement”), among
Alcoa, the Lenders and Issuers party thereto, Citibank, N.A. (“Citi”), as
Administrative Agent for the Lenders and Issuers, and Barclays Bank PLC, as
Syndication Agent.

B. Capitalized terms used herein and not otherwise defined herein shall have the
meanings assigned to such terms in the Credit Agreement.

C. Pursuant to Section 2.20(a) of the Credit Agreement, Alcoa has invited each
of the Acceding Lenders, and each of the Acceding Lenders desires, to become a
party to the Credit Agreement and to assume the obligations of a Lender
thereunder. Each Acceding Lender is entering into this Agreement in accordance
with the provisions of the Credit Agreement in order to become a Lender
thereunder.

Accordingly, the Acceding Lenders, Alcoa and the Administrative Agent agree as
follows:

SECTION 1. Accession to the Credit Agreement. (a) Each Acceding Lender, as of
the Effective Date, hereby accedes to the Credit Agreement and shall thereafter
have the rights and obligations of a Lender thereunder with the same force and
effect as if originally named therein as a Lender.

(b) The respective Commitment of each Acceding Lender shall equal the amount set
forth opposite its signature hereto.

(c) The amount of each Acceding Lender’s Commitment hereby supplements Schedule
2.01(a) to the Credit Agreement.

SECTION 2. Representations and Warranties, Agreements of Acceding Lenders, etc.
Each Acceding Lender (a) represents and warrants that it has full power and
authority, and has taken all action necessary, to execute and deliver this
Agreement and to become a Lender under the Credit Agreement; (b) confirms that
it has received a copy of the Credit Agreement, together with copies of the most
recent financial statements delivered pursuant to Section 5.01 of the Credit
Agreement and such other documents and information as it has deemed appropriate
to make its own credit analysis and decision to enter into this Agreement
independently and without reliance upon the Administrative Agent, any other
Agent or any Lender; (c) confirms that it will independently and without
reliance upon the Administrative Agent, any other Agent or any Lender, and based
on such documents and information as it shall deem appropriate at the time,
continue to make its own credit decisions in taking or not taking action under
the Credit Agreement; (d) agrees that it will perform, in accordance with the
terms of the Credit Agreement, all the obligations that by the terms of the
Credit Agreement are required to be performed by it as a Lender and
(e) irrevocably appoints Citi as Administrative Agent under the Credit
Agreement. Each Acceding Lender authorizes the Administrative Agent to take such
actions on its behalf and to exercise such powers as are delegated to the
Administrative Agent by the terms of the Credit Agreement, together with such
actions and powers as are reasonably incidental thereto.

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SECTION 3. Effectiveness. (a) This Agreement shall become effective as of
July 28, 2008 (the “Effective Date”), subject to the Administrative Agent’s
receipt of (i) counterparts of this Agreement duly executed on behalf of each of
the Acceding Lenders and Alcoa and (ii) the documents required to be delivered
by Alcoa under the penultimate sentence of Section 2.20 of the Credit Agreement.

(b) Upon the effectiveness of this Agreement, the Administrative Agent shall
give prompt notice thereof to the Lenders.

SECTION 4. Foreign Lenders. If any Acceding Lender is organized under the laws
of a jurisdiction outside the United States, it will provide, following the
Effective Date, the forms specified in Section 2.18(g) of the Credit Agreement,
at the times specified therein, duly completed and executed by such Acceding
Lender.

SECTION 5. Counterparts. This Agreement may be executed in multiple
counterparts, each of which shall constitute an original, but all of which, when
taken together, shall constitute but one instrument.

SECTION 6. Governing Law. THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE WITH
AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK.

SECTION 7. Severability. In case any one or more of the provisions contained in
this Agreement should be held invalid, illegal or unenforceable in any respect,
none of the parties hereto shall be required to comply with such provision for
so long as such provision is held to be invalid, illegal or unenforceable, but
the validity, legality and enforceability of the remaining provisions contained
herein and in the Credit Agreement shall not in any way be affected or impaired.
The parties hereto shall endeavor in good-faith negotiations to replace the
invalid, illegal or unenforceable provisions with valid provisions the economic
effect of which comes as close as possible to that of the invalid, illegal or
unenforceable provisions.

SECTION 8. Notices. All communications and notices hereunder shall be in writing
and given as provided in Section 10.01 of the Credit Agreement. All
communications and notices hereunder to each Acceding Lender shall be given to
it at the address set forth under its signature hereto.

[Signature pages follow]

 

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IN WITNESS WHEREOF, the Acceding Lenders, Alcoa and the Administrative Agent
have duly executed this Agreement as of the day and year first above written.

 

Commitment:

$50,000,000

  US BANK, NATIONAL ASSOCIATION,   by  

/s/ Kenneth R. Fieler

  Name:   Kenneth R. Fieler   Title:   Assistant Vice President   Address:  
Kenneth R. Fieler     Assistant Vice President, Corporate Banking     US Bank
Tower     425 Walnut Street, 8th Floor     ML CN-OH-W8     Cincinnati, OH 45202
    Tel.:   513-632-3120     Fax:   513-632-2068     Email:  
kenneth.fieler@usbank.com

 

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[SIGNATURE PAGE TO ALCOA ACCESSION AGREEMENT DATED AS OF JULY 28, 2008]

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Commitment:

$50,000,000

  SOCIETE GENERALE,   by  

/s/ Eric E.O. Siebert, Jr.

  Name:   Eric E.O. Siebert, Jr.   Title:   Managing Director   Address:  
Kimberly Metzger     Director     Societe Generale     190 S. LaSalle Street,
Suite 3850     Chicago, IL 60603     Tel.:   312-894-6235     Fax:  
312-894-6201     Email:   kimberly.metzger@sgcib.com

 

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[SIGNATURE PAGE TO ALCOA ACCESSION AGREEMENT DATED AS OF JULY 28, 2008]

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Commitment:

$50,000,000

  THE GOVERNOR AND COMPANY OF THE BANK OF IRELAND,   by  

/s/ Aoife Quinn

  Name:   Aoife Quinn   Title:   Authorized Signatory   by  

/s/ Lisa Stewart

  Name:   Lisa Stewart   Title:   Authorized Signatory   Address:   Elaine
Crowley / David Rafferty     Bank of Ireland Corporate Banking     B2, Head
Office     Lower Baggot Street     Dublin 2, Ireland     Tel.:   + 353 1 604
4712 / 4253     Fax:   + 353 1 604 4798     Email:   elaine.crowley@boimail.com
/       david.rafferty@boimail.com

 

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[SIGNATURE PAGE TO ALCOA ACCESSION AGREEMENT DATED AS OF JULY 28, 2008]

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ALCOA INC., by  

/s/ Peter Hong

Name:   Peter Hong Title:   Vice President and Treasurer

 

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[SIGNATURE PAGE TO ALCOA ACCESSION AGREEMENT DATED AS OF JULY 28, 2008]

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CITIBANK, N.A., as Administrative Agent, by  

/s/ Andrew Sidford

Name:   Andrew Sidford Title:   Vice President

 

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[SIGNATURE PAGE TO ALCOA ACCESSION AGREEMENT DATED AS OF JULY 28, 2008]

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NOTICE OF PROSPECTIVE LENDERS’ COMMITMENTS

JULY 28, 2008

CITIBANK, N.A.,

    as Administrative Agent under the

    Credit Agreement referred to below

2 Penns Way, Suite 110

New Castle, Delaware 19720

Attention: Bank Loan Syndications

 

  Re: Alcoa Inc.

Ladies and Gentlemen:

Reference is made to the Credit Agreement, dated as of October 2, 2007 (as the
same may be amended, restated, supplemented or otherwise modified from time to
time, the “Credit Agreement”), among Alcoa Inc. (“Alcoa”), the Lenders and
Issuers party thereto, Citibank, N.A., as Administrative Agent for the Lenders
and Issuers, and Barclays Bank PLC, as Syndication Agent. Capitalized terms used
herein and not otherwise defined herein are used herein as defined in the Credit
Agreement.

Pursuant to Section 2.20(a) of the Credit Agreement, each of Alcoa and each of
the Prospective Lenders named below hereby gives you notice that each such
Prospective Lender extends a Commitment under the Credit Agreement in the amount
indicated below opposite the name of such Prospective Lender (each an “Extended
Commitment”), effective as of the Effective Date (as defined in the Accession
Agreement dated as of July 28, 2008 among Alcoa, each of the Prospective Lenders
named below and the Administrative Agent):

 

Prospective Lender

  

Extended

Commitment

    

US Bank, National Association

   $50,000,000   

Societe Generale

   $50,000,000   

The Governor and Company of the Bank of Ireland

   $50,000,000   

The Extended Commitment of each of the above Prospective Lenders shall become
effective as of the Effective Date, subject to the Administrative Agent’s
receipt of (i) this Notice of Prospective Lenders’ Commitments duly executed on
behalf of Alcoa and each of the above Prospective Lenders and (ii) the documents
required to be delivered by Alcoa under the penultimate sentence of Section 2.20
of the Credit Agreement.

[Signature pages follow]

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IN WITNESS WHEREOF, Alcoa and each of the Prospective Lenders named below have
caused this Notice of Prospective Lenders’ Commitments to be executed by their
respective authorized officers as of the day and year first above written.

 

ALCOA INC. By:  

/s/ Peter Hong

Name:   Peter Hong Title:   Vice President and Treasurer

[Signature page to Notice of Prospective Lenders’ Commitments]

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US BANK, NATIONAL ASSOCIATION By:  

/s/ Kenneth R. Fieler

Name:   Kenneth R. Fieler Title:   Assistant Vice President

[Signature page to Notice of Prospective Lenders’ Commitments]

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SOCIETE GENERALE By:  

/s/ Eric E.O. Siebert, Jr.

Name:   Eric E.O. Siebert, Jr. Title:   Managing Director

[Signature page to Notice of Prospective Lenders’ Commitments]

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THE GOVERNOR AND COMPANY OF THE BANK OF IRELAND By:  

/s/ Aoife Quinn

Name:   Aoife Quinn Title:   Authorized Signatory By:  

/s/ Lisa Stewart

Name:   Lisa Stewart Title:   Authorized Signatory

[Signature page to Notice of Prospective Lenders’ Commitments]

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NOTICE OF INCREASE IN COMMITMENT

JULY 28, 2008

CITIBANK, N.A.,

    as Administrative Agent under the

    Credit Agreement referred to below

2 Penns Way, Suite 110

New Castle, Delaware 19720

Attention: Bank Loan Syndications

 

  Re: Alcoa Inc.

Ladies and Gentlemen:

Reference is made to the Credit Agreement, dated as of October 2, 2007 (as the
same may be amended, restated, supplemented or otherwise modified from time to
time, the “Credit Agreement”), among Alcoa Inc. (“Alcoa”), the Lenders and
Issuers party thereto, Citibank, N.A., as Administrative Agent for the Lenders
and Issuers, and Barclays Bank PLC, as Syndication Agent. Capitalized terms used
herein and not otherwise defined herein are used herein as defined in the Credit
Agreement.

Pursuant to Section 2.20(a) of the Credit Agreement, each of Alcoa and the
Lender named below hereby gives you notice that such Lender causes its
Commitment under the Credit Agreement to be increased in the amount indicated
below (the “Increase”), effective as of the Effective Date (as defined below):

 

Lender

 

Increase in

Commitment

 

Commitment

after the Increase

The Northern Trust Company

  $25,000,000   $50,000,000

The Increase shall become effective as of July 28, 2008 (the “Effective Date”),
subject to the Administrative Agent’s receipt of (i) this Notice of Increase in
Commitment duly executed on behalf of Alcoa and The Northern Trust Company and
(ii) the documents required to be delivered by Alcoa under the penultimate
sentence of Section 2.20 of the Credit Agreement.

[Signature page follows]

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IN WITNESS WHEREOF, Alcoa and The Northern Trust Company have caused this Notice
of Increase in Commitment to be executed by their respective authorized officers
as of the day and year first above written.

 

ALCOA INC. By:  

/s/ Peter Hong

Name:   Peter Hong Title:   Vice President and Treasurer THE NORTHERN TRUST
COMPANY By:  

/s/ Ashish S. Bhagwat

Name:   Ashish S. Bhagwat Title:   Vice President

 

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