A double chamber SrCe0.95Yb0.05O3-a, proton conducting membrane reactor was used in order to explore N2O and NO cathodic reduction, over Pd cathodes, by hydrogen generated from steam electrolysis at the anode. Non-Faradaic enhancement of N2O decomposition was observed at cathodic overpotentials, and vertical bar Lambda vertical bar values above unity were achieved. Electrochemically transferred protons not only liberated the active sites from oxygen ad-atoms but also activated inactive, at open circuit, sites to adsorb and dissociate N2O. In the NO-containing reactant mixtures the NO reduction rate was always negligible at open circuit since Pd was essentially inactive towards NO dissociation. Nevertheless, Pd became active at cathodic overpotentials, and vertical bar Lambda vertical bar values equal to unity revealed a Faradaic enhancement according to the "decomposition" mechanism. In presence of C3H8 and O-2 data suggested a "reduction" type of mechanism. (C) 2009 Elsevier B.V. All rights reserved.