A new nanocomposite, titanium aluminum carbonitride/amorphous-carbon thin film was prepared by radio-frequency (rf) plasma-enhanced chemical-vapor deposition using titanium tetrachloride, aluminum trichloride, methane, and nitrogen as reactants. Hydrogen was used as carrier gases. A substrate temperature of 500 degreesC and an rf power of 100 W were used in all depositions. The films were characterized by x-ray powder diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results show that nanograins of titanium aluminum carbonitride were embedded in an amorphous-carbon matrix. The nanograins had a (200) preferred orientation with columnar cross-section morphology. Mechanical properties were analyzed by nanoindentation and hardness was demonstrated to increase via this microstructure design approach. The effects of microstructure on mechanical properties were also determined.