R.f. power and d.c. bias have been applied simultaneously to the target in a conventional magnetron sputtering system in order to control the growth kinetics of TiNx films by using an Ar-N-2 gas as sputtering gas. The deposition rate of reactively sputtered films is increased with the target d.c. bias because of the target current increase with target bias. The composition of the films was measured using X-ray photoelectron spectroscopy. It has been found that the compositional N:Ti ratio of sputtered films is increased by decreasing the target d.c. bias. The formation of TiNx films is possible at low ion energies compared with the d.c. mode magnetron sputtering.