A palladium membrane has been prepared by electroless plating on the surface of a Porous Stainless Steel disk. The disk surface was modified with WO3 to prevent metal penetration into palladium layer and hence a membrane with nano-sized pores could be obtained. The mean thickness of the resulting Pd membrane on the modified disk was 12 mu m. The permeability and selectivity of membrane was investigated. The permeability tests at 773 K showed that the membrane prepared was highly selective towards hydrogen. Additionally aging tests showed hydrogen permeation through the membrane was independent of time. (C) 2009 Elsevier B.V. All rights reserved.