The water gas shift (WGS) reaction of a syngas mixture has been carried out in a tubular palladium membrane reactor at a temperature of 410-414 degrees C. A composite palladium-porous stainless steel membrane. 29 mu m thick, obtained by electroless plating, has been first extensively tested with pure gases (H(2), He, CO(2)) and syngas mixtures in the 310-455 degrees C temperature range and up to 800 kPa. Long-term stability of the membrane in H(2) at 400 degrees C has also been checked over a period of 1200 h. The membrane has been then used for WGS tests in a membrane reactor. The membrane reactor, packed with a pulverized Fe/Cr commercial catalyst, has been operated at a reaction pressure of 100-600 kPa in the counter-current mode, with a nitrogen sweep-gas. The reactor has been fed with a shift gas mixture with a 7.6% CO concentration and H(2)O/CO ratio in the 2.7-3.6 range. The membrane reactor was able to achieve up to the 85.0% of CO conversion, while only the 37% as a maximum, was reached with the traditional reactor in the same operating conditions. Up to the 82% of hydrogen has been recovered with a purity exceeding the 97%. (C) 2010 Elsevier B.V. All rights reserved.