An improved process for production of dialkyldithiophosphinic acid including sulfurizing a purified dialkylphosphinic acid by: reacting a hypophosphorous acid or salt with a stoichiometric excess of an alpha olefin in the presence of a free radical initiator to form a reaction product comprising monoalkylphosphinic acid and dialkylphosphinic acid; adding sufficient aqueous base to the reaction product to i) form the salts of the phosphinic acids, and ii) establish an aqueous phase and an organic phase, wherein a monoalkylphosphinic acid solubilizes into an aqueous phase; separating the organic phase from the aqueous phase; acidifying the organic phase and removing the olefin from the organic phase; isolating the purified dialkylphosphinic acid product; and sulfurizing the purified dialkylphosphinic acid product to form a dialkydithiophosphinic acid. The present invention also provides a process for preparing purified dialkylthiophosphinic chloride, and a process for preparing purified dialkylmonothiophosphinic acids.