AbstractThe syntheses of phosphorylated allyl ester monomers and polymers are described and some factors relevant to allyl ester polymerization are discussed. Successful phosphorylations of chloromethylpolystyrene (cross‐linked with 2% divinylbenzene), polyvinyl chloride and cannel coal, by the use of phosphorus trichloride in conjunction with a Friedel‐Crafts catalyst (AlCl3) have been conducted, and a technique for phosphorylation of a phenol‐formaldehyde resin matrix is described. Alkaline hydrolysis of triallyl phosphate and diallyl allylphosphonate polymers results in monobasic resins with a sodium‐hydrogen exchange capacity of 4.5 mequiv. per g. of acid resin. Oxidative hydrolyses (contact with concentrated nitric acid) of the phosphorylated product obtained from the reaction of chloromethylpolystyrene with phosphorous trichloride results in a dibasic resin with an over‐all exchange capacity of 8.5 mequ