Abstract: A phosphate amine salt and a phosphonic amine salt were synthesized. The load carrying capacity, anti wear, friction reducing, anti corrosion and anti rust behaviors of the synthetic products as additives in liquid paraffin and a commercial mineral oil 500SN were investigated. The anti wear and friction reducing properties of the synthetic additives were compared with those of sulphurized olefin (SO), Zinc dialkyldithiophosphate(ZDDP) and dibutyl phosphate (DBP) as well. The elemental composition and chemical states of the wear scar on the SAE52100 steel ball was examined by means of X ray photoelectron spectroscopy (XPS). The results show that phosphate amine salt and phosphonic amine salt additives have much better extreme pressure properties than the conventional S, P, and/or Cl containing additives. XPS analysis of the wear scar indicates that PN agents function to reduce friction and wear mainly by forming tribochemical reaction film on the lubricated steel surface, which is accompanied by adsorption of the additives on the steel surface as well.