The electrochemical synthesis of some new sulfonamide derivatives was carried out via the electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione (1) in the presence of arylsulfinic acids (2a and 2b) as nucleophiles. The results show that, the electrogenerated phthalazine-1,4-dione (1ox) participates in a Michael type addition reaction with 2a or 2b and via an EC mechanism to produce the corresponding sulfonamide derivatives. This method provides a one-pot procedure for the synthesis of new sulfonamide derivatives of potential biological significance in good yields without using toxic reagents at a carbon electrode in an environmentally friendly manner.