A new carbon paste electrode chemically modified with TiO2 nanoparticles (TiO2NP-MCPE) is constructed and used for the selective and sensitive electrochemical determination of trace amounts of clozapine (CLZ). The effect of carbon paste composition, working solution pH and scan rate were studied with this modified electrode. The presence of TiO2 nanoparticles in the carbon paste increased the available surface area of the electrode and improved the sensitivity by enhancing peak currents. The electrochemical behavior of the modified electrode and the mechanism of the oxidation of CLZ were investigated using cyclic voltammetry (CV). From the slope of the Tafel plot the alpha value was found 0.57. Using adsorptive differential pulse voltammetry (AD-DPV) at optimum parameters a linear dynamic range of 0.5-45 mu M clozapine was observed with detection limit of 61.0 nM. In addition, the CLZ and thioridazine were determined simultaneously using TiO2NP-MCPE in AD-DPV. In AD-DPV measurements, used TiO2NP-MCPE, the oxidation peak potentials of CLZ and thioridazine was separated about 260 mV. The voltammograms showed two anodic peaks at 370 and 630 mV vs. Ag/AgCl, corresponding to the oxidation of CLZ and thioridazine, respectively. Finally, this method was used for determination of CLZ in dozapine tablets with satisfactory results. (C) 2012 Elsevier Ltd. All rights reserved.