Nanostructured CoSi with the diameter of 1-3 nm on graphene have been successfully synthesized by metal organic chemical vapor deposition (MOCVD) of Co(SiCl3)(CO)(4) as a precursor supported on graphene. Pt electrocatalysts are then loaded on the CoSi/graphene composites (Pt/CoSi-graphene) using an intermittent microwave heating method. The above materials are characterized by XRD, Raman, TEM, EDS and cyclic voltammograms measurements. The results show that Pt/CoSi-graphene gives 3.2 times higher peak current density than that of commercial Pt/C(TKK) electrocatalyst at the same Pt loadings. In addition, Pt/CoSi-graphene shows superior activity and stability to commercial Pt/graphene for methanol oxidationin in acidic media. The improved catalytic activity and stability is due to the synergistic effect (electron-donating) of CoSi to Pt. Since Pt/CoSi-graphene carries higher catalytic activity and stability comparing with Pt/graphene, less Pt will be required for the same performance and it will in turn reduce the cost of fuel cell electrocatalyst. (C) 2015 Elsevier Ltd. All rights reserved.