This paper presents a modified version of the well-known model of Bernardi and Verbrugge which was developed to simulate the behavior of polymer electrolyte fuel cells. The modified version is based on a different treatment of the electrokinetic model equations, the Butler-Volmer equations. Such equations are analytically integrated in the reactive regions of the electrodes, eliminating the main nonlinear terms in the full mathematical model. It is shown that the modified Bernardi-Verbrugge model is as accurate as the original model, that it allows an extension of the cell current density over which it is possible to find solutions, that the full numerical procedure is very stable, and that the simulations are up to three orders of magnitude faster than those performed with the original model. © 2001 The Electrochemical Society. All rights reserved.