The catalytic activity of a hybrid compound, nickel(salen)-POM (1), consisting of nickel(salen) [salen = N,N'-bis(salicylidene)ethylenediamine] complex covalently linked to a lacunary Keggin-type polyoxometalatc, K-8[SiW11O39] (POM), was studied in the epoxidation of various olefins in acetonitrile, using hydrogen peroxide as an oxygen source. This is the first time that nickel(salen)-POM has been used as a catalyst for the liquid phase epoxidation of olefins. The complex (1) can catalyze epoxidation of various olefins including non-activated terminal olefins. The effect of reaction parameters such as temperature, solvent and oxidant on the epoxidation of styrene were investigated. In comparison with the corresponding Ni(salen), the higher yields obtained in the epoxidation of olefins catalyzed by nickel (salen)-POM. (c) 2007 Published by Elsevier B.V.