Amwphow and hydrogenated amolphous carbon films were prepared on a g h s substrate using DC magnetron sputtering deposition in gas mixtures of H2 and Ar having different H2 content. T n b~ emission and fiction were measured in a fictional system by sliding an AeOs ball across carbon films in a dry air atmosphere. Wear behavior of the carbon films was investigated by observing t h worn sufaces with a scanning electron microscope (EM) and an atomic force microscope (AFM). Carbon films prepared with low level H2 gas contents showed low fiction and low wear in the production of low electron missions. With i n t m d i a t e level H2 gas contents, transitions of fiction, wear intensity and electron emissions occurred from low to high. At high H2 gas content, high fiction and high wear occurred to produce high electron emissions. These wear mechanisms and the tnbomission behavior are discussed in relation to the sujace energy and internal compressive stress of the carbon film.