Electrochemical oxidation of catechol (1) has been studied in the presence of benzoylnitromethane (2a), benzoylacetonitrile (2b), benzoylacetone (2c) and dibenzoylmethane (2d) as nucleophiles in water/acetonitrile (60/40, v/v) solution, by means of cyclic voltammetry and controlled-potential coulometry. The results indicate the participation of electrochemically generated o-benzoquinone (1ox) in the Michael addition reaction with nucleophiles 2a–d, to form the corresponding benzofuran derivatives. Based on the EC mechanism, the observed homogeneous rate constants (kobs) of the reaction of o-benzoquinone (1ox) with CH-acid nucleophiles (2a–d) were estimated by comparing the experimental cyclic voltammograms with the digitally simulated results. The calculated observed homogeneous rate constants (kobs) were found to vary in the order 2a > 2b > 2c > 2d.