The water gas shift (WGS) catalytic membrane reactor (CMR) incorporating a composite Pd-membrane and operating at elevated temperatures and pressures can greatly contribute to the efficiency enhancement of several methods of H(2) production and green power generation. To this end, mixed gas permeation experiments and WGS CMR experiments have been conducted with a porous Inconel supported, electroless plated Pd-membrane to better understand the functioning and capabilities of those processes. Binary mixtures of H(2)/He, H(2)/CO(2), and a ternary mixture of H(2), CO(2) and CO were separated by the composite membrane at 350, 400, and 450 degrees C, 14.4 bar (P(tube) = 1 bar), and space velocities up to 45,000 h(-1). H(2) permeation inhibition caused by reversible surface binding was observed due to the presence of both CO and CO(2) in the mixtures and membrane inhibition coefficients were estimated. Furthermore, WGS CMR experiments were conducted with a CO and steam feed at 14.4 bar (P(tube) = 1 bar), H(2)O/CO ratios of 1.1-2.6, and GHSVs of up to 2900 h(-1), considering the effect of the H(2)O/CO ratio as well as temperature on the reactor performance. Experiments were also conducted with a simulated syngas feed at 14.0 bar (P(tube) = 1 bar), and 400-450 degrees C, assessing the effect of the space velocity on the reactor performance. A maximum CO conversion of 98.2% was achieved with a H(2) recovery of 81.2% at 450 degrees C. An optimal operating temperature for high CO conversion was identified at approximately 450 degrees C, and high CO conversion and H(2) recovery were achieved at 450 degrees C with high throughput, made possible by the 14.4 bar reaction pressure. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.