The oxygen reduction reaction (ORR) has been studied using different types of carbon supported Pt-Co alloys and (Pt-Co)-Cs2.5H0.5PW12O40 composite electrodes. The composite electrodes, prepared using different methods, have been characterized by RDE voltammetry in O-2 saturated acidic media. The composite electrodes show better performances toward ORR than the commercial pristine catalyst in terms of mass activities and half wave potentials. The composite prepared using the in house Pt-Co alloy shows the higher catalytic activity. The analysis of XRD spectra of the home-made Pt-Co alloy reveals the presence of different phases (fct and fcc) that probably justify the better catalytic properties. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.