TiN coatings were deposited on c-Si substrates by the vacuum arc evaporation process varying the substrate bias potential in the range from 100 to 450 V. The distribution in the crystalline grain size, the residual intrinsic stress and the hardness of the coatings were analyzed as a function of the substrate bias potential. Using the Warren-Averbach method, the X-ray diffractograms were analyzed to obtain the behavior of the crystalline size distribution and root mean square microstrains as a function of substrate bias potential. Vicker's microindentation measurements were performed to obtain the substrate/coating hardness. The hardness of the TiN coatings as a function of crystalline grain size shows a behavior according to the Hall-Petch relation. (C) 2003 Elsevier Science B.V. All rights reserved.