Graphene oxide (GO) and Au(III) are electrochemically co-reduced in ionic liquid to prepare graphene/Au nanocomposites. The electrochemical reduction processes were recorded by I-t curves, which indicate that the simultaneous reduction of GO and Au(III) is favorable to each other. The X-ray diffraction patterns confirm the complete reduction of GO. The scanning electron microscopy and transmission electron microscopy results reveal that Au particles with a diameter of about 10 nm are dispersed uniformly on the electrochemically reduced graphene (ER-G). Furthermore, the electrochemical activity of ER-G/Au nanocomposites was evaluated and the ER-G/Au nanocomposites electrode demonstrates great electrochemical catalytic activity and stability. (C) 2010 Elsevier B.V. All rights reserved.