Hollow CuNi nanocrystals supported on reduced graphene oxide (RGO-CuNi) are synthesized by in situ co-reduction of Cu2+, Ni2+ and graphene oxide (GO) in a one-pot reaction. The as-synthesized RGO-CuNi nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, inductively coupled plasma optical emission spectrometry, Raman spectroscopy, and magnetic measurement. It is revealed that hollow CuNi nanocrystals with an average size of about 35.1 nm are uniformly deposited on the surface of RGO nanosheets. The formation mechanism of the hollow CuNi nanostructures is also proposed based on the galvanic displacement reaction. The as-synthesized RGO-CuNi nanocomposite exhibits excellent electrocatalytic performance toward the oxidation of glucose in alkaline media, and also shows superior catalytic activity and recycling stability toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Moreover, the RGO-CuNi catalysts can be easily recollected from the reaction system by an external magnetic field due to their considerable saturation magnetization. It is anticipated that loading hollow nanostructures on RGO sheets would open up a new avenue for developing multifunctional catalysts with low cost and high catalytic performance. (C) 2014 Elsevier B.V. All rights reserved.