Dynamic response performance of Proton Exchange Membrane (PEM) fuel cells affects its durability and reliability significantly In this study, in order to promote the PEM fuel cell dynamic response performance, RuO2 center dot xH(2)O/CNTs was prepared by sol-gel method and then sprayed onto the Pt/C electrode surface to form the cathode. The RuO2 center dot xH(2)C/CNTs prepared was characterized by Transmission Electron Microscopy (TEM), which shows the average particle size of RuO2 center dot xH(2)O is 3 nm and particulates are well distributed Performance of single cells with and without RuO2 center dot xH(2)O/CNTs at the cathode under various operating conditions such as different gases pressure, air stoichiometry and relative humidity was studied using cyclic voltammetry, electrochemical impedance spectra (EIS) and polarization curve techniques When the fuel cell modified with RuO2 center dot xH(2)O/CNTs was operated at lower pressure and higher air stoichiomotery, a faster and more stable dynamic response could be found It was also found that the humidity of cathode inlet gas had a significant effect on fuel cell performance Adding 0 1 mg/cm(2) RuO2 center dot xH(2)O/CNTS (RuO2 center dot xH(2)O 11%) composite material not only slightly increases the single cell performance but also dramatically improves the dynamic response performance, revealing that RuO2 center dot xH(2)O/CNTs can buffer the voltage undershoot whenever the current increases instantly (C) 2009 Published by Elsevier Ltd on behalf of Professor T Nejat Veziroglu