The electrochem. oxidn. of benzoic acid (BA) was studied on boron-doped diamond electrodes on acid medium by cyclic voltammetry and bulk electrolysis. In the potential region where the supporting electrolyte is stable, reactions occur, resulting in the loss of activity due to electrode fouling. Electrolysis at high anodic potentials in the region of electrolyte decompn. causes complex oxidn. reactions that lead to incineration of BA. There is no indication of electrode fouling. Salicylic acid, 2,5-dihydroxybenzoic acid, and hydroquinone were detected at trace level by HPLC as sol. products during the electrolysis of BA. [on SciFinder (R)]