A novel electrochemical sensor based on a new kind of nanomaterials Mo6S9-xIx nanowires modified glassy carbon electrode (GCE) was constructed for simultaneous determination of cadmium(II), lead(II) and copper(II) using differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters such as the modified amount, pH, deposition time and deposition potential were optimized. Under the optimal conditions, the stripping peak currents increase linearly with increasing concentrations of Cd(II), Pb(II) and Cu(II) ions in the ranges of 0.5 similar to 150 mu g.L-1, 1.5 similar to 450 mu g.L-1 and 0.8 similar to 240 mu g . mu g.L-1, 1.5 similar to 450 mu g.L-1 and 0.8 similar to 240 mu g.L-1, respectively. And the limits of detection (S/N = 3) are estimated to be 0.10 mu g.L-1 for Cd (II), 0.45 mu g.L-1 for Pb(II) and 0.20 mu g.L-1 for Cu(II), which are two orders of magnitude lower than those obtained at the unmodified electrodes. Most importantly, the sensor has been successfully applied to the determination of trace metal ions in the tap water samples. This developed electrochemical sensor exhibits high sensitivity, good stability and reproducibility. (C) 2014 Elsevier Ltd. All rights reserved.