Exhibit 31.2
Certification
Pursuant to Section 302 Of The Sarbanes-Oxley Act Of 2002
(Chapter 63, Title 18 U.S.C. Section 1350(A) And (B))
I, Mark Nelson, certify that:
| 1. | I have reviewed this quarterly report on Form 10-Q/A of XOMA Ltd.; |
| 2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report. |
| Date: September 11, 2008 | /s/MARK NELSON |
| | Mark Nelson |
| | Principal Financial Officer |
