α-Silicon polyoxomolybdates in combination with an iodonium salt and/or a silane are used to generate phenyl and/or silyl radicals as well as silylium cations upon UV light irradiation. These species can initiate the radical photopolymerization of acrylates, the cationic photopolymerization of epoxides and the photopolymerization of epoxy/acrylate blends (i.e. for the synthesis of interpenetrated polymer networks) thereby leading to the formation of polyoxometalate/polymer hybrid materials. The mechanical properties of e.g. the polyether films are affected by the presence of polyoxometalate in the matrix as shown by their dynamic mechanical analysis (DMA). The photochemical mechanisms are studied by steady state photolysis, cyclic voltammetry, and electron spin resonance techniques.