A bio-ethanol mixture was used for carrying out the ethanol steam reforming (ESR) reaction in a Pd-Ag dense membrane reactor (MR) in order to produce a CO-free hydrogen stream. The MR was packed with a commercial Co-based catalyst and the experimental tests were performed between 250 and 400 degrees C, at 1.5 bar of reaction pressure and in both co-current and counter-current flow configurations. Experimental results in terms of ethanol conversion, products selectivities and CO-free hydrogen yield are reported as well as a discussion on the CO-free hydrogen stream recovered in the permeate side of the MR (directly suitable for feeding a PEM fuel cell system) is also presented. Moreover, a comparison with a traditional reactor (TR) working at the same MR operating conditions is realized, pointing out that the MR is able to give ethanol conversions higher than the TR in all the experimental tests realized in this work. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.