The methane steam-reforming reaction has been investigated from a modeling point of view, considering the effect of different parameters on methane conversion. In particular, we point our attention mainly toward the influence of the different retentate and permeate flux configurations on both methane conversion and hydrogen recovery. Both methane conversion and hydrogen recovery are higher in the membrane reactor operated in the countercurrent mode than in the cocurrent mode. A comparison between a traditional steam-reforming process and a membrane reactor process has also been made. The use of a membrane reactor can simplify the process scheme, and the operating temperature and the fuel consumption are lower than those of a traditional system.