The thermal stability of stainless steel supported silica membranes in the presence of hydrogen was observed by comparing nitrogen permeance before hydrogen permeation test with that after hydrogen permeation test. The silica composite membranes significantly failed in the presence of hydrogen above 250degreesC, resulting from the reduction of metal oxide such as iron oxide formed on the surface of stainless steel substrates. To improve the thermal stability of the membranes, the interface between the coating layer and the stainless steel, which is an important factor in the membrane failure, was minimized by introducing new technique of the soaking-rolling method. As a result, the thermal stability of the stainless steel supported silica membranes was substantially improved linked with high H-2/N-2 selectivity. (C) 2004 Elsevier B.V. All rights reserved.