The chemistry of a-ketophosphonates has been reviewed. New applications of a-ketophosphonates in synthesis are described. 1, 3-Diketoalkylphosphonates have been used to prepare phosphinyl - substituted heterocycles and imines derived from a-aminophosphonates have been used in syntheses of pyridyl phosphonates and in 1, 3-dipolar and carbanion additions to olefins. Acetylenic phosphonates have been prepared from a-phosphinylvinyl phosphates. The reactions of a-ketophosphonates with trialky phosphites are described; their use in 'ene' reactions has been investigated. N, N, N', N' -Tetramethylphenylphosphonic diamide has been ortho-lithiated and the resulting aryl-lithium reacted with a series of electrophiles. The Pummerer reaction intermediate from methyl diethoxy- phosphinylmethyl sulphoxide has been trapped with l-alkenes and the oxidative desulphurization of the products investigated.