The effects of thermal treatments in air and in N-2/Ar atmospheres on H-2 permeation of self-supported 5 and 10 mu m Pd/23 wt% Ag membranes prepared by magnetron sputtering are investigated. After hydrogen flux stabilization at 300 degrees C, the membranes were annealed in air at 300 degrees C or in N-2/Ar at 300/400/450 degrees C for 4 days and then tested for hydrogen permeation at 300 degrees C. Air treatment generally induced improved permeation for all thicknesses. For the treatments in N-2/Ar, permeability generally depends on the heat treatment temperatures and on the thickness of the membranes. In particular, hydrogen permeation was improved for treatment temperature of 450 degrees C, but reduced for 400 degrees C and below. An average permeability of 2.61 +/- 0.4 mol/(m s Pa-0.5) for permeation measurements at 300 degrees C before heat treatment and an apparent activation energy of similar to 7kJ/mol obtained in the range of 300-450 degrees C for N-2/Ar treated membranes are comparable to some of the values in the literature. Substantial permeance difference was observed for the measurements in the temperature range, 300-450 degrees C between the membranes heat treated in air at 300 degrees C and in N-2/Ar at 450 degrees C. The measured permeance between 300 and 450 degrees C for the 10-mu m membranes heat treated in air at 300 degrees C remains practically unchanged, i.e. E-a approximate to 0. (C) 2009 Elsevier B.V. All rights reserved.