Titanium Nitride (TiN) thin film was deposited on ß-type Ti-15Mo-3Nb-3Al-0.2Si alloy plates by RF magnetron sputtering method. The effect of nitrogen flow rate on the structure and properties of the TiN thin films were studied. The preferred orientation of TiN thin films changed from (111) to (200) as the nitrogen flow rate increased due to the effect of the kinetic energy of the bombarding particles. The coating thickness was found to decrease with increasing nitrogen concentration, which also favors (200) orientation with increasing nitrogen flow rate. With increase of nitrogen flow, the morphology of the TiN thin films films changed from characteristic pyramidal shaped grains to columnar-shaped grains. The roughness analysis of the coating shows that the average roughness of the coating decreased with increasing nitrogen flow rate. The increase of hardness with increasing nitrogen flow rate is attributed to the decrease in grain size. © (2012) Trans Tech Publications, Switzerland.