This paper presents the behaviour of a proton exchange membrane fuel cell (PEMFC) connected to a static dc-dc converter. Two different models of the PEM fuel cell are obtained from static measurements and impedance spectroscopy. The paper points out the necessity to use different models according to the type of study performed on the system. The comparison of models at high semiconductors switching frequency (25 kHz) is illustrated. Various experimental results obtained on a 500 W PEMFC test bench are compared with simulation ones to illustrate the accuracy of the proposed models. (c) 2005 Elsevier B.V. All rights reserved.