On the basis of a case study, we first analyze the voltage transient properties of a fuel cell stack. We then propose a semi-empirical model, which has been validated by three test runs in the paper. The results obtained in this paper show that the model-computed values correctly fit the experimental data and ensure that the suggested model is highly able to reflect the transient properties of the fuel cell stack voltage. The advantage of this model lies in a simple structure, represented by a small number of parameters. Therefore, it can easily be applied to the simulation of vehicle dynamics for design aims. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.