Kinetics study of the oxygen reduction reaction (ORR) taking place on carbon supported Co@Pt/C core-shell nanocatalysts, were characterized by using the rotating ring-disc electrode (RRDE) technique and results compared to that of Pt/C (Etek). The supported catalyst was successfully synthesized through a simple procedure through sequential colloidal chemical reduction of Co and a galvanic replacement by Pt. X-ray diffraction results of the Co Pt/C nanoparticles showed important structural changes which can be responsible for the observed enhanced catalytic activity. XRD Rietveld refinement confirmed the presence of metallic Pt and Co in the relative weight fraction of 12 wt% and 88 wt% respectively, as well as a Pt lattice contraction (i.e. 3.8741 angstrom) and Co lattice expansion (i.e. 3.6170 angstrom). Electrochemical results support the formation of a core-shell structure with double enhanced ORR activity and similar peroxide generation of the Co@Pt/C catalyst with respect to Pt/C (Etek). Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.