We prepared a novel catalyst support material consisting of polydopamine (PDA)-coated polymeric carbon nitride (g-C3N4) on a reduced graphene oxide (RGO) (PDA@CN-G) using graphene oxide, melamine and dopamine via an aqueous solution process. The resulting support possesses an excellent electrochemically accessible surface area, various porous structures, and a high nitrogen content. When platinum ions were anchored on its surface, Pt/PDA@CN-G hybrid electrocatalysts (serving as an electrode in direct methanol fuel cells) exhibited an improvement in catalytic activity (1.5 times), high poison tolerance toward CO (3.1 times), and long-term durability (1.7 times) compared to those of Pt-anchored reduced graphene oxide catalyst. The catalyst's superior performance could be attributed to its morphological characteristics, having a porous nanostructure and the synergetic effect afforded by the g-C3N4 layer and PDA coating. Thus, the hybridized composite support is potentially an effective approach to obtain a high activity and stable catalyst support material for fuel cell applications. (C) 2016 The Electrochemical Society. All rights reserved.