In the development of environmental friendly and highly efficient energy processes, membrane reactors hold an important role for their ability to carry out, simultaneously and in the same unit, the separation and reaction steps. Taking advantage of the synergies deriving from this coupling, they achieve comparable results to the conventional reactors at less severe conditions. A sensitivity analysis has been developed in order to define the role of some variables on the performance of a membrane reactor for maximizing the system efficiency. The behaviour of a membrane reactor has been investigated by means of a two-dimensional mathematical model applied to the water-gas shift reaction. By depending on operation feed pressure, a specific choice of both sweep gas flow rate and temperature can limit the occurring of dangerous temperature hot spots without compromising the performance of the system. The catalyst distribution coupled with an efficient heat exchange across the membrane have been investigated as possible technical solutions adequate to control hot spots along the membrane reactor. (C) 2007 Elsevier B.V. All rights reserved.