Abstract: The feasibility of controlling the tribological behavior of metal/ceramics rubbing couples by means of applying an external electric field was explored.The results show that the friction coefficients of the rubbing couples composed of ceramic materials, alumina and quartz glass, and metals, brass, stainless steel and carbon steel, change substantially when an external D C. voltage is applied under the lubrication condition of zinc stearate water emulsion. The change in friction coefficient caused by the electric field depends on the voltage and the polarity and materials type. Preliminary analysis indicates that the electro-friction phenomena could be related to the balance of generation and destruction of the boundary lubrication film, which was influenced by the external voltage. It was also found that friction coefficient could be controlled with a feed-back voltage modulation method.