Thin (40 nm and 160 nm) Cr-N coatings were deposited on steel by reactive magnetron sputtering deposition, varying the N(2) flow. The coatings were characterized in the as-deposited condition and after annealing in air at 500 degrees C for 1 h, by X-Ray Diffraction, Transmission Electron Microscopy, Raman and Fourier Transform Infrared spectroscopies. Hardness was measured by nanoindentation. Coatings have a nanocrystalline microstructure with the phase shifting from Cr(2)N to CrN, increasing grain size, thermal stability and resistance to oxidation with increasing N(2). Also intrinsic coating hardness is influenced by both N(2) flow during deposition and film thickness, as a result of changes in phase composition and microstructural properties. (C) 2011 Elsevier B.V. All rights reserved.