The preparation of thin (similar to 1mum), mechanically stable, and relatively pinhole-free zeolitic membranes is described. Nanocrystalline zeolite Y (100-200 nm) is used as the starting material and coated onto a porous alumina substrate. Pinholes within the membrane are filled with a positive photoresist. Upon illumination of the photoresist, only the light-exposed parts are solubilized, whereas the photoresist within the cracks is not affected, thereby sealing them. The leak properties of such membranes were tested using Rhodamine 123 dye, and levels of about 0.5% leaking as compared to the non-photoresist-coated membranes were found. Accessibility of the intrazeolitic volume was examined by ion exchange and for optimally illuminated membranes was comparable to uncoated membranes. Charge transport through the membrane by electron hopping by a self-exchange process involving bipyridinium ions was demonstrated. The electron transfer was initiated using a photochemical Ru(bpy)(3)(2+)-EDTA system.