The methanol steam reforming (MSR) reaction to produce hydrogen was studied from an experimental point of view in membrane reactors (MRs). In order to investigate the behaviour of methanol conversion, the influence of the membrane characteristics, the sweep gas flow rate, as well as the influence of the operating temperature and the different flux configurations were analysed. Experimental results, in terms of methanol conversion as well as hydrogen production and gases selectivity in MRs and a traditional reactor (TR), are proposed. A set of values of key parameters to obtain the maximum hydrogen production is given. (c) 2006 Elsevier B.V All rights reserved.