The H(2)S-tolerance of Palladium-Copper nanoparticle catalysts supported on carbon black employed on PEMFC anodes operating on H(2)S-contaminated anode feeding streams is described. The anode feeding consists of 80% H(2), similar to 20% N(2) (in vol.), and 8 ppm H(2)S. Catalyst performances were evaluated by estimating the cell potential reduction due to H(2)S contamination through lifetime tests. It is found that the H(2)S-tolerance of PdCu catalysts depends on the concentration of copper, as confirmed by a catalyst pre-leaching procedure. This methodology is employed in order to remove copper atoms from the catalyst surface, which is confirmed by energy dispersive X-ray spectroscopy and X-ray diffraction techniques. This method generates catalysts with lower copper content and higher susceptibility to H(2)S. Moreover, it is proposed a new and effective catalytic activity recovering technique to restore the performance of PdCu catalysts after H(2)S exposure. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.