A novel electrochemical sensor for methyl parathion based on silicate- cetyltrimethylammonium bromide nanocomposite film has been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry. Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased. Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship between the peak current and methyl parathion concentration was obtained in the range from 1.0 x 10(-7) to 1.0 x 10(-4) mol L(-1) with a detection limit of 1.04 x 10 (-8) mol L(-1) (S/N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in real samples.