T1-xAlxN films could be successfully deposited on high-speed steel and silicon wafer by plasma-assisted chemical vapor deposition (PACVD) technique using a gaseous mixture of TiCl4, AlCl3, H-2, Ar, and N-2 instead of NH3 as a nitrogen source. Comparative studies on micro-hardness, microstructure, and oxidation behavior between TiN and T1-xAlxN film were conducted in this work. Incorporation of a certain amount of Al to TiN film (Ti0.88AlxN film) enhanced the micro-hardness value up to 2800 HK (kg mm(-2)), which was largely increased one compared with 1400 HK (kg mm(-2)) for pure TiN film. Ti1-xAlxN films were polycrystalline and maintained the B1-NaCl structure of TiN. Al incorporation into TiN, however, caused the lattice parameter of the TiN crystal to decrease, grain size to be finer, and changed the strong (200) preferred orientation of TiN to a relatively random-oriented microstructure. Those microstructural changes with Al addition were reasoned for the large increase of micro-hardness of the Ti1-xAlxN film. The Ti1-xAlxN him was found to be more resistive against high-temperature oxidation than a pure TiN film.