The hydrogen permeation characteristics of alloy membranes based on Pd-coated V90Al10 alloy membrane have been investigated in the pressure range 1-3 atm under pure hydrogen and hydrogen -carbon dioxide gas mixture at 450 degrees C. Hydrogen permeation experiments have been confirmed that hydrogen flux was 21.1 ml/min/cm(2) for a Pd-coated V90Al10 alloy membrane (thickness: 0.5 mm) using pure hydrogen as the feed gas. It has been found that Pd-coated V90Al10 alloy membranes exhibit good resistance to hydrogen embrittlement in pure hydrogen atmosphere. After different hydrogen permeation flux tests under different pressure condition in presence of hydrogenecarbon dioxide gas mixture, the characteristics of the Pd-coated V90Al10 alloy membranes were examined by ex-situ analysis techniques. The loss of cell performance observed in the presence of hydrogenecarbon dioxide gas mixture is mainly attributed to both physical and chemical degradations of membrane, which led to structural changes in the Pd-coated V90Al10 xalloy membrane. (C) 2011 Elsevier B. V. All rights reserved.