The synthesis and characterization of Pt-Ni nanoparticles with different Ni:Pt atomic ratios and supported on multi-walled carbon nanotubes (MWCNTs) for oxygen reduction reaction (RRO) is investigated. The crystal structure and the elemental analysis of Pt-Ni/ MWCNTs nanocatalysts are characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS), respectively. The morphology of these nanocatalysts is observed by transmission electron microscopy (TEM). The results reveal that Pt-Ni nanocatalysts with a nanoparticle size ranging from 6 to 7 nm are immobilized on the surface of MWCNTs. The kinetics and mechanism of the ORR were analyzed in a 0.5 M H2SO4 solution. The cyclic voltammetry response indicates that Pt-Ni/MWCNTs catalyst displays a higher performance than Pt/MWCNT, which may be due to the alloy of Ni species in Pt-Ni systems, demonstrating that they are promising materials for using in fuel cells. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.