Hydrogenated amorphous carbon films have been prepared from CH4, H2, and Ar mixtures by plasma‐enhanced chemical‐vapor deposition. Films with various physical properties were obtained from different deposition conditions. The deposition parameters varied included H2flow rates, Ar flow rates, total pressures, substrate temperatures, and power densities. Effects of each deposition parameter on the microstructures and the kinetics involved in the formation of each film are discussed. In addition, relations between deposition conditions, microstructures, and the optical properties are reported.