The preparation of thirty-six 0, O-dialkyl S-(carbamoylalkyl) phosphorodithioates is described. Several new or improved synthetic routes are employed, most importantly one utilizing S-carboxymethyl O, O-dimethyl phosphorodithioate. The product of displacement of a phoephorothioate salt on an a-haloamide is shown to have the phosphorothiolate structure.