In this study, the production of hydrogen by methanol steam reforming in a membrane reactor (MR) was simulated using a one-dimensional mathematical model. The model assumes axially dispersed plug-flow with pressure drop for the retentate side, and plug-flow behaviour with no axial dispersion and no pressure drop for the permeate side. The finite volume method was used for space discretization, being the dependent variables determined with high-resolution schemes. Two types of membranes were simulated, namely a carbon molecular sieve membrane (CMS) and a palladium membrane (Pd). The simulation results showed that the CMS membrane reactor presents higher hydrogen recoveries, while the Pd membrane reactor has the advantage of producing a pure hydrogen stream. It was also studied a membrane reactor with two membrane sections, one made of CMS and the other made of palladium. This new configuration revealed some advantages compared to the reactor equipped with either membrane type, and namely it showed the highest hydrogen recovery. (C) 2009 Elsevier B.V. All rights reserved.