Palladium acetate and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were dissolved in chloroform to forma homogeneous solution. Using this solution, thin polymer template film with embedded Pd catalyst was coated on a porous alpha-Al2O3 hollow fiber substrate. The Pd in the template film was used as the catalyst for electroless plating of Pd membranes. After the template was removed by heat treatment, the thin Pd membranes without any intermediate layers and substrate penetration were synthesized successfully. The as-synthesized Pd composite membranes of thickness less than 5 mu m not only have a very high hydrogen permeance/permeability but also have a good hydrogen selectivity. Moreover, the good membrane stability was verified by the long-term operation under the condition of hydrogen permeation and the gas exchange cycles between pure hydrogen and pure helium. The good membrane stability was interpreted by estimating the shear stress of the special membrane configuration with small gap between Pd membrane and porous substrate layer. (C) 2007 Elsevier B.V. All rights reserved.