An investigation was carried out on the effect of the varying CH4 concentration for the synthesis of carbon nitride using microwave plasma CVD from CH4-N-2 gas mixture. Crystalline particles were observed for 1% CH4 concentration. The deposit changed to a film covered with whiskers for 10% CH4 concentration. The composition calculated from the AES spectrum of the deposit at 1% CH4 Concentration indicated a nitrogen concentration of 57.5%. In the XRD pattern of the deposit at 1% CH4 concentration, the peaks of alpha-C3N4 (301), (401) planes were observed. No Raman peak of carbon was observed in Raman spectrum of the deposit for 1% CH4 concentration. C-N and C-N bonded structures were observed in the XPS spectra. (C) 2004 Elsevier B.V. All rights reserved.