Disodium phenyl phosphate is a monophenyl ester of phosphoric acid. It is used as tool compound to study the efficacy of phosphatases. Hydrolysis of phenyl phosphate by milk phosphatases was used to used to indicate whether milk has been adequately pasteurized or whether it has been contaminated with raw milk after pasteurization. Phenyl phosphate was also used as a molecular fragment for fragment-based drug discovery of Src SH2.