Nickel porous membrane was successfully made for hydrogen separation or metal support for Pd and/or Pd-alloy dense membrane. Ni porous membrane made by uniaxial pressing has so small and uniform pore size to be the support of dense membrane. We fabricated the Ni porous membrane with two kinds of Ni powder (average particle size of 0.15 and 5 mu m). It was clarified that the broad distribution of particle size is very important to the packing degree of membrane and selectivity of H-2 and H-2 permeation was contributed by Knudsen and surface diffusion from the results of permeation test under room temperature to 200 degrees C. With various particle size as well as the increasing compressed pressure, we could obtain more compactness, thereby achieving the satisfactory selectivity of H-2. (C) 2005 Elsevier B.V. All rights reserved.