Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt Manuscript received 10 October 1984, accepted 21 June 1985 The different substituted-formazans (1a -k) are electrochemically studied in benzo­nitrile with 0.1 M tetrabutylammonium perchlorate as supporting electrolyte using DC and cyclic voltammetry. They are oxidised in a single irreversible two-electron process to the corresponding tetrazole cation. The reduction occurs in one irreversible two-electron or two irreversible one-electron waves according to the nature of the subs­tituent, forming the dianion.