Addressed herein is the synthesis of binary CuPt alloy nanoparticles (NPs), their assembly on reduced graphene oxide (rGO), Vulcan XC72 (VC) and their hybrid (rGO-VC) to be utilized as electrocatalysts for fuel cell reactions (HOR and ORR) in acidic medium and PEMFC tests. The synthesis of nearly-monodisperse Cu45Pt55 alloy NPs was achieved by using a chemical reduction route comprising the reduction of commercially available metal precursors in a hot surfactant solution. As-synthesized Cu45Pt55 alloy NPs were then assembled on three support materials, namely rGO, VC and rGO-VC) via liquid phase self-assembly method. After the characterization, the electrocatalysts were prepared by mixing the yielded materials with Nafion and their electrocatalysis performance was investigated by studying CV and LSV for HOR and ORR in acidic medium. Among the three electrocatalysts tested, Cu45Pt55/rGO-VC hybrid showed the highest catalytic activity with ECSA of 119 m(2) g(-1) and mass activity of 165 mA mg(pt)(-1). After the evaluation of electrochemical performance of the three prepared electrocatalysts, their performance was then evaluated in fuel cell conditions. In similar to electrochemical activities, the Cu45Pt55/rGO-VC hybrid electrocatalyst showed a superior fuel cell performance and power output by providing a maximum power of 480 mW cm(-2) with a relatively low Pt loading (0.28 mg cm(-2)). Additionally, the Cu45Pt55/rGO-VC hybrid electrocatalyst exhibited substantially better activity as compared to Pt/rGO-VC electrocatalyst. Therefore, the present study confirmed that alloying Pt with Cu enhances the catalytic activity of Pt metal along with the help of beneficial features of rGO-VC hybrid support material. It should be noted that this is the first example of studying PEMFC performance of CuPt alloy NPs supported on rGO, VC and rGO-VC hybrid. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.