Abstract: Saturated solution of dicyandiamide in acetonitrile was selected as the electrolyte in an attempt to deposit carbon nitride films onto glass substrates coated with indium tin oxide （ITO-coated glass）. The result of X-ray photoelectron spectroscopy （XPS） showed that the maximum value of the N/C atomic ratio in the films was 1.22, quite close to the stoichiometric value of C₃N₄. Fourier transform infrared （FTIR） spectroscopy supported the existence of C—N, （C）N covalent bonds. Optical band gap E_opt of CN_x films determined by Tauc's relation was wide, and the E_opt of the sample obtained at 50 ℃, 1 250 V was 2.32 eV. It was found that carbon nitride films of high nitrogen content could be obtained under the conditions of voltages from （1 100 V） to （1 300 V） and temperatures from 30 ℃ to 50 ℃.