The Pd–Ag films, with a total thickness of <2.2 μm, were deposited by electroless plating on the inside of α-alumina membranes from SCT. The H 2 permeances through separated Pd–Ag layers were poor and heating conditions were investigated to improve the H 2 permeances through the metal films. The heating temperature, heating time and heating environment all had a significant effect on the H 2 permeance and the H 2 to N 2 selectivity of the Pd–Ag films. The films were oxidised at 310°C for 1 h after heat treatment in Ar at 550°C, and then reduced in H 2. This additional surface modification step more than doubled the H 2 permeance through the film and only created a moderate amount of membrane defects as indicated by the increase in the N 2 permeance. After the heating process, the membranes were characterised from 250 to 410°C using both a sweep gas and a positive pressure difference.