Catalytic performance of the 5 wt.% Pd/C and 5 wt.% PdC0.14/C catalysts for formic acid electrooxidation was compared under potentiodynamic (0.06-1.0 V vs. RHE, sweep rate 50 mV s(-1)) and potentiostatic (0.2 and 0.3 V vs. RHE) regimes in 0.5 M HCOOH + 0.1 M H2SO4 solution at 25 degrees C. The non-stoichiometric palladium carbide catalyst demonstrates superior catalytic performance and stability during HCOOH electrooxidation as compared to the unmodified Pd/C precursor. The observed phenomenon is explained in terms of modification of electronic and adsorption properties of palladium caused by the embedding of carbon atoms in the interstitial cites of the crystalline lattice of Pd nanoparticles. (C) 2012 Elsevier B.V. All rights reserved.