Methane steam re-forming is one of the most important chemical processes in hydrogen and syngas production. Simulation of reactors with parallel-flow and counterflow configuration has been performed to study the methane steam re-forming reaction in a packed-bed inert membrane reactor (PBIMR). In this kind of reactor complete methane conversion can be achieved by means of the total removal of hydrogen from the reaction products. In the model a dense Pd membrane was simulated, assuming an infinite permselectivity to hydrogen. Membrane reactor performance was compared to that of a conventional fixed-bed reactor. The effect on the degree of conversion was analyzed for different parameters such as temperature, reactor pressure, feed and sweep flow rate, feed molar ratio, membrane thickness, and space velocity. Comparison with experimental data of Shu et al. (1994) showed a good agreement. An analysis of the results indicated that the choice of operating conditions requires a complex process strategy.