A new method ha.s beon reported for the preparation of dibutylphosphinic acid and its esters based on the reaction of dibutylphosphine oxide with water or alcohols and a base in the presence of carbon tetrachloride.As dialkylphosphonate and monoal-kylphosphonate, dialkylphosphi.nc; oxide can also effect oxidative phosphinylation of hydroxy compounds though the yield is rather poor.It is in consequence of the enhancement of the electron density of phosphorus atom by the inductive effect of alkyl groups.It is thus proposed that the reaction operates by an ionic process rather than a radical mechanism.Dibutylphosphinic acid obtained in this way is proved to be identical with that synthesized by classical methods in its behaviour in paper chromatography, paper electrophoresis, potentiometric titration and infrared spectra.With dicyclohegylamin), quinine as well as S-bonzylisothiouronium chloride dibutylphosphinic acid forms crystalline salts with sharp melting pointy.