Lubrication by in situ-formed films of soft metals has been discovered for several metal (gold, silver, and copper) alkyl phos-phonates and gold dialkylphosphorodithioates. This novel lubricating function of oil soluble compounds has been demonstrated in bench wear tests. Deposition of metal occurs only on the rubbing contact surfaces and it is found to be more prevalent on the surface of higher temperature. Highest reductions in wear are observed when the film forms only on one surface, so that in effect, steel is sliding against a film of soft metal.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975