Reactive interpenetrating polymeric network membranes in both flat-sheet and tubular form have been synthesized by photopolymerization of methacrylate monomers in microporous polypropylene substrates. Many different monomers can be utilized in the synthesis of sheet-form membranes while for tubular membranes only water-insoluble monomers can be used at present. Reactions of the epoxy group incorporated in the membranes via 2,3-epoxypropyl methacrylate are discussed and functionalizations with mercaptoethanol are shown to give a conversion of 87% of the theoretically available groups. Scanning electron microscopic analysis shows that the synthesized membranes are totally non-porous. The elemental homogeneity in cross-sections of functionalized membranes was investigated by energy dispersive X-ray analysis.