Abstract The electrochemical behavior of some 1,3,4-thiadiazole derivatives substituted at C5 (carbon number five in thiadiazole ring) with a hydrazono group has been studied at a dropping mercury electrode (DME) in different pH values. Controlled potential electrolysis (CPE) in alkaline medium, cyclic voltammetry (CV), ultraviolet spectra (UV) and pKa studies confirmed the proposed mechanism.