Tetrahedral amorphous carbon nitride (ta-C:N) films obtained by filtered cathodic vacuum arc deposition have been investigated by Near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The C K (carbon K) edge NEXAFS spectra clearly revealed the increase of C=N bonds with the increase of nitrogen concentration. The C K edge NEXAFS analysis further showed that the content of the surface defect (mainly C-H bonds) decreased with the increase of nitrogen in the films. As the nitrogen concentration increased a pronounced change in the pi* features were observed at the N K (nitrogen K) edge. The origin of the N K edge pi* peaks are mainly due to the formation of C-N bonds and nitrogen substitution in the graphite network. Polarization dependent NEXAFS measurements showed an angular distribution of CN bonds. The electrical resistivity of the ta-C:N films decreased at higher nitrogen concentration and this may be from the development of graphite-like structures in these films. The electrical measurements were confirmed further with electrochemical measurements. (c) 2005 Elsevier B.V. All rights reserved.