A thermodynamic analysis of the CO2 hydrogenation to methanol where competitive reactions take place is presented for a membrane reactor (MR) where methanol was selectively removed. A non-isothermal mathematical model was written to simulate a micro-porous MR. Zeolite membranes with different values of the CH3OH and H2O permeances were considered in the MR modelling. The effect of temperature, pressure and species permeation on the conversion, selectivity and yield was analysed. A higher CO2 conversion and CH3OH selectivity can be reached by the use of an MR. An increased CH3OH yield allows to reduce the consumption of reactant and also to operate at lower pressures and higher temperatures, a fact, which favours the kinetics reducing the residence time and the reactor volume. The MR with the highest CH3OH/H2O permeance ratio resulted in better selectivity and yield of CH3OH with respect to the other MR characterised by a higher conversion.