Carbon nitride (CNx) thin films have been deposited onto Si(100) (for structural and mechanical analyses) and M42 high-speed-steel (for tribological measurement s) substrates at room temperature by closed-field unbalanced magnetron sputterin g. The mechanical and tribological properties of these films were highly depende nt on the N/C concentration ratio that was adjusted by the F(N2)/F(Ar) flow-rate ratio at fixed substrate biasing of -60V during deposition. The films were char acterized by employing scanning electron microscopy (SEM), atomic force microsco py (AFM), nano-indentation measurements, X-ray photoelectron spectroscopy (XPS), Raman scattering and Fourier transform infrared (FTIR) spectroscopy, pin-on-dis c tribometer, scratch tester, and Rockwell-C tester. The results showed that the N content in the films increased with the N2 pressure. However, the maximum N/C ratio obtained was 0.25. The nanohardness was measured to be in the range of 11 .7-20.8GPa depending on the N/C ratios. The XPS N 1s spectra showed the existenc e of both N-C sp2 and N-C sp3 bonds in films. Raman and FTIR spectra exhibited t hat N-C bonds were fewer when compared to other N-C bonds. The friction coeffici ent of the film deposited onto steel substrate with N/C=0.26 was measured to be ~0.08 and for film with N/C=0.22 a high critical load of 70N was obtained. The t ribological data also showed that the wear rates of these films were in the rang e of ~10-16m3/Nm, indicating excellent wear resistance for CNx films. Carbon nitride (CNx) thin films have been deposited onto Si (100) (for structural and mechanical analyzes) and M42 high-speed-steel (for tribological measurements) substrates at room temperature by closed-field unbalanced magnetron sputtering. and tribological properties of these films were highly dependent on nt on the N / C concentration ratio that was adjusted by the F (N2) / F (Ar) flow-rate ratio at fixed substrate biasing of -60V during deposition. The films were char acterized by employing scanning electron microscopy (SEM), atomic force microsco py (AFM), nano-indentation measurements, X-ray photoelectron spectroscopy (XPS), Raman scattering and Fourier transform infrared (FTIR) Scratch tester, and Rockwell-C tester. The results showed that the N content in the films increased with the N2 pressure. However, the maximum N / C ratio obtained was 0.25. The nanohardness was measured to be in the range of 11 .7 -20.8 GPa depending on the N / C r The XPS N 1s spectra showed the existenc e of both NC sp2 and NC sp3 bonds in films. Raman and FTIR spectra exhibited t hat NC bonds were fewer when compared to NC bonds. The t ribological data also showed that the wear rates of these films were in the rang e of ~ 10-16m3 / Nm, indicating excellent wear resistance for CNx films.