CNx thin film with high nitrogen content was prepared on ITO conductive glass substrates by cathode electrodeposition, using dicyandiamide (C2H4N4) in acetone as precursors. The surface morphologies, atomic bonding state, and chemical composition were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. The CNx particles got nanometer level with the average size of 80 nm. The maximum value of the N/C atomic ratio was more than 1. Carbon and nitrogen existed mainly in the form of tetrahedral C-N bonds, with a few C=N bonds. From UV-Vis absorption spectrum, we found that during near-ultraviolet area the deposited CNx films appeared nonlinear optical absorption phenomena, and the ultraviolet light (200-280 nm) could be transmitted. The electrical resistivities of the films were in the range of 10(12)-10(16) Omega CM. (C) 2003 Elsevier Science B.V. All rights reserved.