The reduction of N-thioamidoimidates (1) has been examined in aprotic media at a mercury electrode. As shown by cyclic voltammetry at fast scan rates and controlled potential electrolysis, an overall irreversible one electron transfer is followed by a rapid second order chemical reaction leading to a dimer which involves to thiazolo[5,4-d]thiazole by intramolecular cyclization. (C) 2004 Elsevier B.V. All rights reserved.