Ternary Ti-Zr-N thin films were synthesized by rf-reactive sputtering in Ar–N2 plasma. Effects of the substrate temperature in the sputtering process on the microstructures of Ti-Zr-N thin films were investigated using SEM, TEM, XRD and AES techniques. The hardness of the Ti-Zr-N film increases as the substrate temperature in reactive sputtering increases. The reactive sputtered Ti-Zr-N film is characterized as polycrystalline in nature with two dominant orientations of (111) and (200). A substrate temperature of 300°C is suggested for getting a densely packed film structure with the highest hardness.