This study reports on the hydrogen permeation properties of Pd-Cu alloy membranes at high pressures. A 7 μm thick Pd-Cu alloy membrane was prepared on an alumina-modified porous nickel support (PNS) by our developed magnetron sputtering and Cu-reflow method at 700℃ for 2 hours. The membrane was mounted in a stainless steel permeation cell with a gold-plated stainless steel O-ring. Helium leak testing confirmed that the membrane and membrane module were free of defects. Permeation tests were then conducted using hydrogen at temperatures in the range from 678 to 816 K with a transmembrane pressure difference of 1-20 bars, which showed that the membrane had a hydrogen permeation flux of 1.06 mol m^(-2) s^(-1) at a temperature of 816 K and a pressure difference of 20 bars. EDX analysis was carried out after hydrogen permeation test at 816 K and showed that there was no intermetallic diffusion between the Pd-Cu layer and PNS because the alumina layer inhibited it effectively.