Abstract: The friction and wear behavior of two semi metallic friction materials containing MoS 2 or graphite as the lubricating phase has been investigated on a D MS friction and wear tester. The morphology and elemental compositions of the wear debris have been examined by means of scanning electron microscopy and energy dispersive spectrometry, respectively. The wear mechanism of the friction materials is discussed by taking into account the interaction among the lubricating phase and the other components. As the results, MoS 2 and graphite show difference in terms of the interaction with the other components in the friction materials. The friction material containing MoS 2 show better wear resistance than that containing graphite. This is because MoS 2 as the lubricating component does not enhance pulling out and wear of the steel fiber in the friction material by way of carburization. The wear debris is mainly composed of Fe, Ca, and Sb.