Toxic heavy-metal ions are well known to be severely harmful to human health. Therefore, the development of fast and sensitive methods for their detection has drawn a great attention in recent years. Herein, a sensitive electrochemical platform for the simultaneous determination of Cd2+, Pb2+, Cu2+, and Hg2+ has been constructed based on N-doped graphene (NG) modified electrode using differential pulse stripping voltammetry (DPSV). NG was synthesized by a facile, efficient and green electrochemical method. The structure and composition of NG were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron microscopy (XPS) techniques, chronocoulometry and N-2 adsorption-desorption measurements. The NG modified electrode showed excellent catalytic activity for selective detection of Cd2+, Pb2+, Cu2+, and Hg2+ due to its particular structure and unique electronic properties. Under optimal conditions, the limits of detection were estimated to be 0.05 mu M for Cd2+ and Hg2+, 0.005 mu M for Pb2+ and Cu2+, respectively. Finally, the method was applied to the simultaneous detection of trace metal ions in the tap water samples. (C) 2015 Elsevier B.V. All rights reserved.