Core-shell Cu@Cu2O nanoparticles on reduced graphene oxide (Cu@Cu2O NPs-RGO) nanocomposite were prepared at room temperature by in situ reduction of graphene oxide (GO) and copper sulfate using L-ascorbic acid as reducing agent and then the air oxidation of copper nanoparticles' surface. The Cu@Cu2O NPs-RGO nanocomposite was characterized by infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. Finally, Cu@Cu2O NPs-RGO nanocomposite was used as an efficient and reusable heterogeneous catalyst in N-arylation of N-heterocycles. (C) 2014 Elsevier B.V. All rights reserved.