Microporous membranes and membrane modules have been developed for high temperature separation of hydrogen from other gas molecules. Tubular alpha alumina substrate with 0.7 mu m pore size and 40% porosity was prepared as the membrane substrate and an intermediate alpha alumina layer with pore size of 60 nm and porosity of 39% was formed by dip-coating over the substrate. The gas permeation characteristics as well as the stability of the substrate itself and that with the intermediate layer were respectively evaluated. A procedure of preparing defect-less gamma alumina and silica layers over the substrate was applied to make a highly selective membrane for hydrogen gas. Hydrogen gas permeation values in the range 5E-8 to 5E-6 mol/m(2) s Pa with H-2/N-2 ideal separation factors in the range 30-300 have been measured with the silica membranes. Alumina substrate tubes were also used for fabrication of a tubular bundle, using glass-based sealant materials for joining the substrate tubes to a ceramic endplate. The bundle also was used as a support for silica membrane making. The gas permeation and separation performance of the membrane module was evaluated. (c) 2005 Elsevier B.V. All rights reserved.