Electrochemical oxidation of catechol and some of 3-substituted catechols (1a-c) has been studied in the presence of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (3) as the nucleophile at various pH values in aqueous solution using cyclic voltammetric and controlled-potential coulometric methods. The results revealed that the products derived from catechols (1a-c) participate in Michael addition reactions with 3-methyl-l-phenyl-1H-pyrazol-5(4H)-one (3) via an ECEC mechanism, converts it to form the corresponding pyrazole derivatives (8a-c). The electrosynthesis of these products was carried out at the surface of carbon electrode in an undivided cell under controlled-potential conditions which is an environmentally friendly method. (C) 2015 Elsevier B.V. All rights reserved.