Water-gas shift (WGS) and methanol steam reforming (MSR) were performed in a catalytic membrane reactor configuration using self-supported Pd/23 wt.% Ag membranes of 1.6 mu m thickness. A commercial Cu/ZnO/support catalyst was used. Effects on hydrogen permeation and membrane stability were investigated under the application of relevant conditions. The membranes were studied with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) before and after usage to characterize the surface composition, microstructure and texture. The self-supported membrane configuration allows exploration of the membrane bulk and surface effects without any influence of a porous support. The extremely low membrane thickness means a greater influence of surface processes compared to thicker membranes. (c) 2006 Elsevier B.V. All rights reserved.