AbstractAn amine salt of an alkoxylphosphate (a P‐ and N‐containing organic compound, PN) was synthesised. Its extreme‐pressure, antiwear, and friction‐reducing properties were evaluated as an additive in liquid paraffin and a mineral oil. Tests were performed on a four‐ball friction and wear tester with an AISI 52100 steel ball self‐mated pair and the results were compared with those of sulphurised olefin (SO), zinc di‐n‐butyldithio‐phosphate (ZDDP), and dibutylphosphite (DBP). The morphologies of the worn steel surfaces were observed using a scanning electron microscope, while the binding energies of some typical elements on the worn surfaces were determined using X‐ray photoelectron spectroscopy. The additives were found to increase the load‐carrying capacity and to reduce wear and friction coefficient considerably. PN as an additive exhibits better load‐carrying, antiwear, and friction‐reducing properties than SO, ZDDP, and DBP under