Spent V catalysts from H(2)SO(4) prodn. in various industrial plants were leached with 20% H(2)SO(4) or 10% KOH to recover the SiO(2) support used then for prodn. of new V catalysts by mixing them with resp. amts. of V(2)O(5) and K(2)CO(3). The new catalysts contg. V(2)O(5) (5.78-5.85%), K(2)O (9.68-9.72%) and Fe (0.22-0.70%) were tested for catalytic activity in SO(2)-to-SO(3) oxidn. under lab. conditions. Ability of the catalysts to deactivation increased with increasing the Fe content. The alk. leaching was inefficient in recovering the SiO(2) support.