Abstract: The friction reducing and antiwear behaviors of oil soluble barium oleate and an organic titanate (BLT) as additives in liquid paraffin were investigated with a four ball machine. The synergistic friction reduction and antiwear action of the two compounds as a composite additive was explored with emphasis on revealing the effect of various metal oxides formed on the lubricated steel surface. The chemical states of the typical elements including C, O, Ti, and Ba on the worn steel surface were examined by means of X ray photoelectron spectroscopy. As the results, oil soluble barium salt and BLT in liquid paraffin have obvious synergistic effect in reducing friction and wear. The oxides composed of Ti, Ba and so on contribute to alter the microphysical features of the frictional pair contact surface, thereby to reduce friction and wear.