For the first time, this work describes the electrochemical behavior of chloropromazine as a modifier on the surface of electrodes. The electrochemical properties of chloropromazine in the silica nanoparticles/chloropromazine/Nafion (SNPs/CPZ/Nf) nanocomposite at pH 2-10 were investigated at a glassy carbon electrode. Well defined reversible redox couples were observed in acidic solutions and irreversible in alkaline solutions. The (SNPs/CPZ/Nf) nanocomposite modified electrodes were characterized with a transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The apparent electron transfer rate constant (K-s), transfer coefficient (alpha) and the surface concentration (Pc) were determined by cyclic voltammetry and they were about 0.025 s(-1), 0.50 and 1.26 x 10(-6) mol cm(-2), respectively. Moreover, electrocatalytic oxidation of sulfide on the surface of modified electrode was investigated with cyclic voltammetry and amperometry methods at pH 7. The prepared modified electrode showed several advantages, such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. Moreover, the proposed sensor can be used for sulfide analysis in water samples. (C) 2014 Elsevier B.V. All rights reserved.