An integrated system for hydrogen production via autothermal steam reforming of methanol and consequent power generation in a polymer electrolyte membrane (PEM) fuel cell has been developed and operated at C. P. E. R. I. The pilot plant comprises an autothermal reforming reactor to produce hydrogen, a preferential oxidation reactor (PROX) to reduce CO concentration below 50 ppm and a PEM fuel cell for power generation. The present paper deals with the study of this system, both from an experimental and a theoretical point of view. The experimental work aims to: (a) examine the effect of the reforming temperature on methanol conversion and on the effluent stream concentration, (b) investigate the effect of reaction temperature and O-2/CO ratio on the performance of the PROX reactor, and (c) evaluate the operation of a 10-cell PEM fuel cell, using pure hydrogen and air at three temperature levels. The experimental data are subsequently utilized for the validation of one-dimensional pseudo-homogeneous models that have been developed for the two reactors and also for the identification of the voltage-current characteristic curve of the PEM fuel cell. The validated models are then used to investigate the behavior and explore the interactions, both static and dynamic, among the various process subsystems. (C) 2009 Elsevier Ltd. All rights reserved.