Abstract: C-N thin films have been prepared by ion beam sputtering using pure N2 as discharge gas. The ratio N/C of the films measured by Auger spectrum is 20% on an average. The results of X-ray diffraction and transmission electron microscopy show that β-C3N4 phase exists in the films. Xray photoelectron spectroscopy shows that nitrogen is mostly combined with carbon with triple (C=N) and double (C=N) bonds. The IR absorption shows an absorption bond near 2185 cm-1assigned to the C=N, no trace of C-C bond was observed