This paper describes a model-based controller for the regulation of a proton exchange membrane (PEM) fuel cell. The model accounts for spatial dependencies of voltage, current, material flows, and temperatures in the fuel channel. Analysis of the process model shows that the effective gain of the process undergoes a sign change in the normal operating range of the fuel cell, indicating that it cannot be stabilized using a linear controller with integral action. Consequently, a nonlinear model-predictive-controller based on a simplified model has been developed, enabling the use of optimal control to satisfy power demands robustly. The models and controller have been realized in the MATLAB and SIMULINK environment. Initial results indicate improved performance and robustness when using model-based control in comparison with that obtained using an adaptive controller. (C) 2004 Elsevier B.V. All rights reserved.