Coatings of chromium and chromium nitride with various compositions were deposited on silicon substrates using ion-assisted reactive magnetron sputtering. These coatings were characterized using x-ray diffraction (XRD). Rutherford backscattering (RBS), and spectroscopic ellipsometry (SE). The primary chromium nitride phases (Cr2N and CrN) in the chromium nitride films were identified using XRD. The chemical composition of selected samples was determined from RBS measurements. The refractive indices of Cr, Cr2N, and CrN were deduced from the analysis of the SE data. Based on these refractive indices, ellipsometry was used successfully to identify the microstructure and the roughness of a number of chromium nitride coatings grown under different deposition conditions.