The operational parameters of a H-2/air micro proton exchange membrane fuel cell (PEMFC) with different flow configurations (mesh, serpentine, and interdigitated) were investigated by impedance spectroscopy. The operational parameters include the cell operating temperature and the anode backpressure. The above parameters affected the high frequency straight line as well as the medium frequency and low frequency arcs. The influence in terms of impedance on the dynamic response of the present H-2/air micro fuel cell under different operating conditions and flow geometry were quantitatively measured, which it allows insight into the nature of these effects and consequently a better understanding of the micro PEM fuel cell system that could be helpful for the design and operation of the fuel cell. (c) 2006 Elsevier B.V. All rights reserved.