Two bimetallic Pt-Au catalysts supported on carbon, namely core-shell structured nanoparticles (Au@Pt/C) and alloy-like nanoparticles (AuPt/C), were synthesized and tested for ethanol electrooxidation in acidic environment. The catalysts were characterized by X-ray diffraction; X-ray photoelectron spectroscopy and transmission electron microscopy. Catalytic activity was quantified by anodic CO-stripping voltammetry, and cyclic voltammetry of ethanol electro-oxidation. The electronic interaction between Pt and Au was demonstrated by X-ray photoelectron spectroscopy and the effect was found to be more prominent in the alloy-like PtAu nanoparticles. X-ray diffraction revealed expanded Pt lattice parameter and interatomic distance in the PtAu nanoparticles. The interaction between Pt and Au of PtAu/C and Au@Pt/C samples was the main cause of the enhanced CO tolerance. The stronger Pt-Au interaction and the expanded Pt lattice parameter in alloyed PtAu/C contributed to the higher specific activity towards ethanol electro-oxidation of PtAu/C compared to Au@Pt/C. (C) 2014 Elsevier Ltd. All rights reserved.