We developed a solvothermal process by a reflux method for growing graphitic carbon nitride (g-C3N4) polymer on graphene oxide (GO) to form three-dimensional (3D) flake-like g-C3N4 on a reduced GO (g-C3N4@RGO) hybrid support material. The assynthesized g-C3N4@RGO, depending on the synthesis ratio of GO to melamine, showed excellent specific capacitance (220-258 F g(-1)) at 10 mV s(-1), a very low charge transfer resistance, high N contents (6-18 at.%), and a 3D network structure. Additionally, compared with Pt-loaded reduced GO (Pt/RGO), when Pt was loaded on g-C3N4@RGO for catalysis, Pt nanoparticles (NPs) with diameters of 2-4 nm were found to be uniformly dispersed. In direct-methanol fuel cells (DMFCs), the Pt/g-C3N4@RGO (8:1) nanocatalysts exhibited high utility in terms of their electrochemically active surface area (ECSA) (81.5 m(2) g(-1)), electrocatalytic oxidation current density of methanol (13.7 mA cm(-2)), CO poison tolerance (I-F/I-R = 1.38), and duration stability, compared with Pt/RGO, Pt-loaded Vulcan XC-72 (Pt/C), and Pt-loaded graphite (Pt/Gr). These results demonstrate the potential of as-synthesized g-C3N4@RGO hybrid material as a high-performance catalyst support for fuel-cell applications. (C) 2015 The Electrochemical Society. All rights reserved.