CrNx films were deposited on stainless steel and Si (1 1 1) substrates via medium frequency magnetron sputtering in a N-2 + Ar mixed atmosphere. The influence of N-2 content on the deposition rate, composition, microstructure, mechanical and tribological properties of the as-deposited films was investigated by means of the X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nanoindentation and tribometer testing. It was found that the N atomic concentration increased and the phase transformed from a mixture of Cr2N + Cr(N) to single-phase Cr2N, and then Cr2N + CrN to pure CrN phase with the increase of N-2 content. The Cr 2p(3/2) and N 1s of XPS spectra also confirmed the evolution of phase. Accordingly, all films exhibited a typical columnar structure which lies in the zone T of Thornton Model. The mixed Cr2N and Cr(N) phases showed low hardness and high friction coefficient. Cr2N possessed higher hardness than CrN while CrN exhibited lower friction coefficient. (C) 2010 Elsevier B.V. All rights reserved.