**Exhibit 31.2**

CertificationPursuant

To 18 U. S. C.Section 1350,

As AdoptedPursuant To

Section 302 of the Sarbanes-Oxley Act of 2002

I,William R. Maris, Vice President — Finance and Administration and ChiefFinancial Officer certify that:

1.               Ihave reviewed this quarterly report on Form 10-Q of Cyanotech Corporation;

2.                Based on my knowledge, this reportdoes not contain any untrue statement of a material fact or omit to state amaterial fact necessary to make the statements made, in light of the circumstancesunder which such statements were made, not misleading with respect to theperiod covered by this report;

3.                Based on my knowledge, the financialstatements, and other financial information included in this report, fairlypresent in all material respects the financial condition, results of operationsand cash flows of the registrant as of, and for, the periods presented in thisreport;

4.                The registrant’s other certifyingofficer and I are responsible for establishing and maintaining disclosure controlsand procedures (as defined in Exchange Act Rules 13a-15(e) or 15d-15(e)) forthe registrant and we have:

a)              Designedsuch disclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that materialinformation relating to the registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this report is being prepared;

b)             Evaluatedthe effectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of thedisclosure controls and procedures, as of the end of the period covered by thisreport based on such evaluation; and

c)              Disclosedin this report any change in the registrant’s internal control over financialreporting that occurred during the registrant’s most recent fiscal quarter (theregistrant’s fourth quarter in the case of an annual report) that hasmaterially affected, or is reasonably likely to materially affect, theregistrant’s internal control over financial reporting; and

5.                The registrant’s other certifyingofficer and I have disclosed, based on our most recent evaluation of internalcontrol over financial reporting, to the registrant’s auditors and the auditcommittee of registrant’s board of directors (or persons performing theequivalent function):

a)              Allsignificant deficiencies and material weaknesses in the design or operation ofinternal controls over financial reporting which are reasonably likely toadversely affect the registrant’s ability to record, process, summarize andreport financial information; and

b)             Anyfraud, whether or not material, that involves management or other employees whohave a significant role in the registrant’s internal controls over financialreporting.
| Date:  | September 21, 2007 |                                                                                                                            | William R. Maris       |
|--------|--------------------|---------------------------------------------------------------------------------------------------------------------------------|------------------------|
|   |               | Vice President –  Finance &   Administration,  Chief Financial Officer  (Principal Financial and Accounting   Officer) |
|   |               |                                                                                                                            |
|   |               | By:                                                                                                                             | /s/ Gerald R. Cysewski |   |
|   |               | Gerald R. Cysewski                                                                                                              |
|   |               | As Attorney-in-fact                                                                                                             |
|   |               | (See Exhibit 24.1)                                                                                                              |
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