Nitrides of transition metals, such as Ti, attract significant interest since they find a wide field of applications ranging from cutting tools to electronic device applications. Titanium nitride is broadly used as a hard protective coating for tribologic applications and for high temperature structural materials. In this work we present the results obtained in the growth of the titanium nitride (TiN) thin films in reactive phase by rf magnetron technique on AISI 420 steels. The depositions of TiN were carried out at a pressure of 7 × 10–3 mbar in an atmosphere of N2 and Ar; we took as study parameter the incident power on the target of Ti (99.9). The films were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The study of XRD showed that films grown with power at 200 W are polycrystalline, while films grown between 350 W and 750 W built the (111) plane of the TiN phase in predominant form and at 800 W there is a change of the growth direction to the (200) plane. The analysis of the Energy Dispersive X-ray Spectroscopy (EDXS) indicated that the films grew stoichiometrically. On the other hand, the hardness tests determined that the films have micro-hardness with values that increased with the power applied to the target; the highest value was 2300 Knoops for the films grown at 500 W. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)