The electrochemical oxidation of 1,2-dihydropyridazine-3,6-dione (1) has been studied in the presence of arylsulfinic acids (2a-2c) as nucleophiles in aqueous solutions using cyclic voltammetry as a diagnostic technique. The results showed that the electrochemically generated pyridazine-3,6-dione (1ox) participates in Michael type addition reaction with arylsulfinic acids (2a-2c) via an EC mechanism and is converted to the corresponding new sulfonamide derivatives. In this work, some new sulfonamide derivatives are provided with high yields in aqueous solutions, without toxic reagents and solvents at a carbon electrode in an undivided cell using an environmentally friendly method. (C) 2013 The Electrochemical Society. All rights reserved.