in this communication, a porous stainless steel (PSS) tube was electrolessly plated into Pd-Ag membrane reactor which was used for separating hydrogen produced in an ethanol steam reforming reaction with the addition of oxygen, which has not been reported before. Palladium and silver were deposited on porous stainless steel tube via the sequential electroless plating procedure with an overall film thickness of 20 mu m and Pd/Ag weight ratio of 78/22. Ethanol-water mixture (n(water)/n(ethanol) = 1 or 3) and oxygen (n(oxygen)/n(ethanol) = 0.2 or 0.7) were fed concurrently into the membrane reactor packed with MDC-3. The reaction temperatures were set at 593-723 K and the pressures 3-10 atm. The effect of oxygen addition plays a vital role on the ethanol steam reforming reaction, especially for the Pd-Ag membrane reactor in which a higher flux of hydrogen is required. If oxygen in the feed is not sufficient, it would be possible that steam reforming reaction prevails. Inversely, high 02 addition will shift the reaction scenario to be partial oxidation dominating, and selectivity of CO2 increases with increasing oxygen feed. At high pressure, autothermal reaction of ethanol would be easily reached. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.