STOCK PURCHASE AGREEMENT THIS STOCK PURCHASE AGREEMENT (this Agreement ) is made as of

STOCK PURCHASE AGREEMENT

THIS STOCK PURCHASE AGREEMENT (this Agreement ) is made as of September 19, 2005, by and between OXIS International, Inc., a Delaware corporation

(the Buyer ), Bio Check, Inc., a California corporation (the Company ) and holders of capital stock of the Company set forth on Schedule 1 attached hereto (each individually, a

Stockholder , and collectively, the Stockholders ). Certain capitalized terms used in this Agreement are defined on Exhibit A hereto.

WHEREAS, the Buyer desires to purchase from the Stockholders, and the Stockholders desire to sell to the Buyer, up to all of the issued and

outstanding shares of capital stock of the Company (the Shares ), pursuant to the terms and conditions set forth herein;

NOW, THEREFORE, in consideration of the foregoing recitals and the mutual representations, warranties, covenants and promises contained herein, the adequacy and

sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

1.1 Purchase of Shares at Initial Closing. The initial closing (the Initial Closing ) of the purchase and sale of Shares

hereunder shall take place as soon as all conditions set forth in Article 8 hereof are satisfied or waived. Subject to the terms and conditions of this Agreement, at the Initial Closing, each Stockholder shall sell, transfer, convey, assign

and deliver to Buyer, and Buyer shall purchase from each Stockholder, all of Stockholder s right, title and interest in not less than fifty-one percent (51%) of the Shares set forth next to such Stockholder s name on Schedule 1

attached hereto. Buyer, at its option, may purchase all of the Shares owned by the Stockholders at the Initial Closing. The aggregate consideration to be paid by Buyer if it purchases all of the Stockholders Shares at the Initial Closing shall

be $6,000,000 (the Aggregate Purchase Price ). In the event Buyer purchases less than all of the issued and outstanding Shares at the Initial Closing, it shall pay to the Stockholders such percentage of the Aggregate Purchase Price

equal to the percentage of Shares purchased from the Stockholders (e.g., if seventy-five percent (75%) of the Shares are purchased from the Stockholders at the Initial Closing, the portion of the Aggregate Purchase Price payable at the Initial

Closing shall be $4,500,000). Each Stockholder shall receive a share of the amount of Aggregate Purchase Price paid at the Initial Closing equal to such Stockholder s percentage of the total number of Shares owned by the Stockholders (e.g., if

a Stockholder owns ten percent (10%) of the total Shares owned by the Stockholders, such Stockholder will be entitled to ten percent (10%) of the Aggregate Purchase Price). At the Initial Closing, the Remaining Shares (as defined below), if any,

shall be put in escrow pursuant to the terms of the escrow agreement in the form attached hereto as Exhibit B ( Share Escrow Agreement ). The purchase and sale of Shares hereunder, and all other related transactions and agreements

contemplated herein, shall be collectively referred to herein as the Transaction .

1.2 Purchase of Remaining Shares. To the extent Buyer purchases less than all of the Shares

of the Stockholders at the Initial Closing, Buyer shall use its reasonable best efforts to consummate a Follow-One Financing Transaction (as defined below) and consummate as soon as reasonably practicable the purchase of the remaining Shares of the

Stockholders (the Remaining Shares ) at one or more additional closings (each an Additional Closing and collectively, Additional Closings ), upon sixty (60) days notice of each Additional

Closing, or such other date as agreed to by the Buyer and the Selling Stockholders Representative (as defined in Section 9.8). The purchase price for the Remaining Shares shall equal the pro rata portion of the Aggregate Purchase Price

relating to such Remaining Shares, plus 8% per annum (the Remaining Shares Purchase Price ). For purposes of example only, assuming Buyer purchases fifty-one percent (51%) of the Shares at the Initial Closing, if eighteen (18)

months following the Initial Closing Buyer purchases all of the Remaining Shares, the Remaining Shares Purchase Price shall be $3,292,800 (.49 multiplied by $6,000,000 = $2,940,000, plus interest of $352,800 ($19,600 multiplied by 18)). Each

Stockholder shall receive a portion of such purchase price paid equal to the percentage of the total number of Remaining Shares such Stockholder owns. If Buyer does not purchase all of the Stockholders Shares at the Initial Closing, pursuant to

Section 6.1(b) hereof, then Buyer shall attempt to consummate a Follow-On Financing Transaction, the proceeds of which will be used to purchase the Remaining Shares. If within twelve (12) months following the Initial Closing the net proceeds raised

in the Follow-On Financing Transaction if any is less than the amount of the aggregate Remaining Shares Purchase Price, then the Buyer shall purchase at an Additional Closing or Closings the proportion of the Remaining Shares determined by dividing

the net proceeds of the Follow-On Financing Transaction by the aggregate Remaining Shares Purchase Price. If the Buyer does not purchase all of the Remaining Shares pursuant to the preceding sentence, the Company shall use, to the extent permitted

by applicable Legal Requirements, up to $1.5 million of the Company s EBITDA (as defined below) generated during the twelve (12) month period following the Initial Closing, to purchase or redeem the Remaining Shares for the applicable portion

of the Remaining Shares Purchase Price, provided, however, if all the Remaining Shares are not so purchased or redeemed through the use of up to $1.5 million of the Company s EBITDA during such twelve (12) month period, the Company shall use,

to the extent permitted by applicable Legal Requirements, the Company s EBITDA generated thereafter to purchase or redeem at an Additional Closing or Closings any Remaining Shares for the applicable portion of the Remaining Shares Purchase

Price until such time that all Remaining Shares are purchased or redeemed. Notwithstanding the foregoing, the Buyer shall have the right, but not the obligation, at any time, to purchase any or all of the Remaining Shares for the applicable portion

of the Remaining Shares Purchase Price.

Asset Payments. Commencing as of the Initial Closing Date, Buyer shall pay to the Stockholders an additional amount equal to fifty percent (50%) of the revenue and proceeds received by Buyer or Company derived from the sale or licensing of the

Id-Gene Asset (as defined below) or any Id-Gene Asset related products including, without limitation, antibodies; provided that the foregoing percentage shall be reduced to (a) thirty percent (30%) for the period from the sixth anniversary of

the Initial Closing Date through the tenth anniversary of the Initial Closing Date, (b) fifteen percent (15%) for the period from the tenth anniversary from the Initial Closing Date through the twelfth anniversary of the Initial Closing Date and (c)

zero percent (0%) thereafter, and provided, further, that if following the Initial Closing Date, more than $100,000 of costs and expenses, in the aggregate, are incurred in developing the Id-

Gene Asset, such excess costs and expenses shall be first deducted from the foregoing payments to the Stockholders. The Company and the Stockholders covenant

and agree to execute, consent, approve and do such other acts and things, as the Buyer may reasonably request, to carry out the intent of this Section 1.3, including without limitation, distributing the proceeds of the Id-Gene Asset from the Company

to the Buyer, or from the Company to the Stockholders.

2.1 Time and Place of Closings. The Initial Closing, and any Additional Closings, of the purchase and sale of the Shares provided for in

this Agreement (collectively, the Closings ) shall occur at the offices of Morrison & Foerster LLP, 755 Page Mill Road, Palo Alto, California, at 10:00 A.M. on the day that all of the conditions to closing set forth in

Article 8 are satisfied or waived (other than conditions that are intended to be satisfied at the Closing), or at such other date, time or place as the parties may agree (the Closing Date ).

2.2 Initial Closing Deliveries by Company. At the Initial

Closing, the Company shall deliver the following items, duly executed by Company, all of which shall be in form and substance reasonably acceptable to Buyer:

(a) Share Escrow Agreement. If less than all of the Shares are purchased at the Initial Closing, executed Share Escrow

(b) Purchase Price Escrow

Agreement. Executed Purchase Price Escrow Agreement in the form attached hereto as Exhibit C;

(c) Shareholders Agreement. Executed Shareholders Agreement in the form attached hereto as Exhibit D ( Shareholders

Duly executed Consents of all third parties required by Company and Stockholders to consummate the purchase and sale of the Shares, in form and substance reasonably satisfactory to Buyer, including those Consents listed on Schedule 3.3;

(e) Officer s Certificate. A

certificate executed on behalf of Company by its President or Chief Executive Officer, dated as of the Initial Closing Date, certifying that:

(i) the representations and warranties of Company set forth in this Agreement, or in any written statement or certificate that shall be

delivered to Buyer by Company under this Agreement, are (without giving effect to any materiality qualifications or references to materiality therein) true and correct in all material respects on and as of the date made and as of the Initial Closing

Date as if made on the date thereof (except to the extent such representation or warranty specifies an earlier date), and

(ii) Company has performed all obligations and covenants required to be performed by it under this Agreement and any other agreement or

document entered into in connection herewith prior to the Initial Closing Date;

(f) Secretary s Certificate. A certificate of Company s Secretary

Company s stockholders and its board of directors authorizing the execution, delivery and performance of this Agreement and of all other related agreements and documents required in connection with the consummation of the purchase and sale of

the Shares (collectively, Transaction Documents ); and

(ii) the incumbency of Company s officers executing this Agreement and all other Transaction Documents; and

(g) Certificate of Good Standing. A certificate from the Secretary of State of California as to Company s good standing and

payment of all applicable California income and franchise taxes.

2.3 Initial Closing Deliveries by Buyer. At the Initial Closing, Buyer shall deliver the following items, duly executed by Buyer as applicable, all of which shall be in a form and substance reasonably acceptable to Seller:

(a) Wire Transfer. A wire transfer of

immediately available funds to each bank account designated by each Stockholder in an amount equal to the purchase price payable for the Shares, as determined pursuant to Article 1 hereof (less the Escrow Amount attributable to each such

Stockholder), being sold by such Stockholder at such Closing, and (ii) a wire transfer of the Escrow Amount (as defined below) attributable to each such Stockholder to the Escrow Agent to be held in escrow (the Escrow Fund )

pursuant to the Purchase Price Escrow Agreement;

(b) Employment Agreements. Executed Employment Agreements (as defined below);

(c) Shareholders Agreement. Executed Shareholders Agreement;

(d) Purchase Price Escrow Agreement. Executed Purchase Price Escrow Agreement;

(e) Share Escrow Agreement. If less than all of the

Shares are purchased at the Initial Closing, executed Share Escrow Agreement; and

(f) Officer s Certificate. A certificate executed on behalf of Buyer by its President or Chief Executive Officer, dated as of

the Initial Closing Date, certifying that:

(i) the representations and warranties of Buyer set forth in this Agreement, or in any written statement or certificate that shall be delivered to Company or Stockholders under this Agreement, are true and correct on and as of the date made

and as of the Initial Closing Date as if made on the date thereof (except to the extent such representation or warranty specifies an earlier date), and

(ii) Buyer has performed all obligations and covenants required to be performed by it

under this Agreement and any other agreement or document entered into in connection herewith prior to the Initial Closing Date.

2.4 Initial Closing Deliveries by Stockholders. At the Initial Closing, the applicable Stockholders shall deliver the following items, duly

(a) Shares. Certificates

representing the Shares to be sold in the Initial Closing and any Remaining Shares which shall be held in the escrow pursuant to the Share Escrow Agreement and such executed stock powers as Buyer may reasonably request;

(b) Employment Agreements. Employment Agreements

respecting the employment of each of John Chen and Anna Pao, substantially in the form attached hereto as Exhibits G-1 and G-2 (the Employment Agreements );

(c) Shareholders Agreement. Executed Shareholders

(d) Purchase Price Escrow

Agreement. Executed Purchase Price Escrow Agreement;

(e) Share Escrow Agreement. If less than all of the Shares are purchased at the Initial Closing, executed Share Escrow Agreement; and

(f) Other Documentation. Such other certificates, instruments or documents required pursuant to the

provisions of this Agreement or otherwise necessary or appropriate to transfer the Shares in accordance with the terms hereof and consummate the Transaction.

2.5 Deliveries at Additional Closings.

(a) In the event there is an Additional Closing or Closings, the Buyer shall deliver to Stockholders at any such Closing the items

referenced at Sections 2.3(a) and 2.3(f)(ii).

(b) In the event there is an Additional Closing or Closings, each Stockholder shall deliver to the Buyer at any such Closing (i) a certificate certifying that the representations and warranties made in Article

4 hereof by such Stockholder are true and correct on such Closing Date and (ii) the items referenced at Section 2.4(f).

WARRANTIES OF COMPANY

Except as set forth in the

corresponding sections of the disclosure schedule of Company delivered to Buyer concurrently with the execution and delivery of this Agreement (the Company Disclosure Schedule ) (provided, that if any fact or item disclosed

in any section of Company Disclosure Schedule shall be relevant to any other section of this Agreement, then such fact or item shall be deemed to be disclosed with respect to such other section of this Agreement, but only to the extent to which it

is readily apparent on its face that such fact or item relates), Company hereby represents and warrants to Buyer that, as of the date hereof: