Upon brief cathodic electrolysis in DMF solutions containing a tetraalkylammonium salt, the addition reaction of dialkyl phosphonates to various aromatic aldehydes ketones resulted in an unusual formation of mixed trialkyl phosphates via P-O rearrangement. The formation of alpha-hydroxyalkanephosphonates as the well-known carbonyl adduct was observed for the case of aliphatic carbonyl compounds. The reaction-path is described in terms of the electrocatalytic generation of dialkyl phosphonate anions and an efficient P-O rearrangement in the intermediate adduct anions.