This work focus on the advantages of adding a preferential carbon monoxide oxidation (PROX) reactor to a common methanol steam reforming (SR) membrane reactor (MR). The study was performed by using a one-dimensional mathematical model, assuming axially dispersed plug flow with pressure drop in both retentate and permeate sides. The finite volumes method was used for space discretization, being the dependent variables determined using high-resolution schemes. The simulation results showed clear advantages of the SR + PROX towards the SR membrane reactor in what concerns the amount of CO in the permeate stream. More specifically, the permeate CO concentration in the SR + PROX MR was reduced to levels below 2 ppm, enabling the stream to feed a fuel cell. Additionally, high values of methanol conversion and hydrogen recovery were achieved, and the amount of CO(2) at the permeate side was able to remain below 20% for all simulations. (C) 2010 Elsevier B.V. All rights reserved.