The phosphonate esters shown in Part I to form thick chemical films in elastohydrodynamic contacts have been found to form a viscous reaction product when heated with iron powder. Both this viscous material and also the thick films formed in earlier elastohydrodynamic tests have been analyzed by a variety of chemical techniques and shown to be similar. They appear to consist of iron-phosphate-monoester polymer, with the phosphate acting as a bridge between iron (III) species. This structure is comparable to that observed in metal phosphinate polymers.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985