Pd-Cu-Ni alloy membrane was successfully deposited 4 mu m in thickness on porous nickel support by multitarget sputtering and Cu-reflow technique. The surface of porous nickel support needed not to be modified because it has very uniform and small pore distribution as 33 nm. From the XRD and SEM analysis, it was clarified that the fabricated Pd-Cu-Ni ternary alloy film had Pd-Cu-Ni alloy character and no defects on the surface of thin membrane. The weight composition of Pd:Cu:Ni was 89:4.5:6.5 from EDS analysis. As a result of single gas permeation test using H-2 and N-2, hydrogen permeance increased with an increase of operating temperature and transmembrane pressure difference. Furthermore, hydrogen separation factor with single gas test was infinity indicating pinhole-free palladium-based alloy membrane. In additions, it was so stable that the morphology of the surface was not changed and there were no indications of metal interdiffusion during time-on-stream test for 10 days with the cycling of operating temperature and transmembrane pressure difference. (C) 2005 Elsevier B.V. All rights reserved.