Ti-based binary nitride and ternary nitride films were deposited on cemented carbide by the arc ion plating method and investigated on microhardness, lattice parameter and morphology. Micro-Vickers hardness of TiN, CrN, and ZrN binary films was 2000, 1400, and 1500 HV, respectively. On the other hand, ternary nitrides such as (Ti,Al)N, (TiCr)N, (Ti,Zr)N, and (Ti,V)N with identical atomic ratio against Ti generally had higher hardness of 3100, 3000, 3000, and 2400 HV, respectively. The lattice parameters of both (Ti,Al)N and (Ti,Cr)N were smaller with 4.18 and 4.19 Å. Futhermore, the surface roughness of TiN, CrN, ZrN, (TiAl)N, and (TiZr)N films was all smooth with small number of droplets, while that of (Ti,Cr)N and (Ti,V)N films became rough with large number of droplets. © 2000 American Vacuum Society.