Titanium nitride films were deposited onto the high speed steel substrates by reactive ion plating method The substrate temperature and ;partial pressure of the N₂gas were controlled as process variables. The nitride phases in the films were identified by X-Ray diffraction technique and were observed in a scanning electron microscope. The hardnesses of deposited films were also measured. The phases presented in the coatings could be predicted from nitrogen gas pressure. And the structure modification by ion bombardment during deposition was also observed. The maximum hardness values of 2800-3300 KHN were obtained at the nitrogen pressure of 0.8×10_(-3) torr.