Ultra-thin nickel dense membranes (~0.5 μm) were developed by polishing treatment of porous nickel supports. The polishing treatment involved the use of 400 grit sand paper, 1000 grit, and 1500 grit, which was able to remove the surface pores due to the ductility of the PNS. The hydrogen permeation test showed that 4.53×10.2 mol m-2 s-1 of hydrogen permeation flux through the membrane could be achieved at a temperature of 973K and a pressure difference of 136 kPa. The nitrogen leakage tests confirmed that there were no pinholes on the surface of the ultra-thin nickel dense membrane.