With the aim of better understanding the process of polymerization and depolymerization of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) at polyaniline-modified electrode, the electrochemical behaviour of DMcT and derivatives has first been studied on platinum by potential sweep voltammetry in acetonitrile. Reactions and redox potentials of the dithiol, thiolate, dithiolate and dimer forms of DMcT have been characterized. The reaction mechanism and kinetics of the disulphide-thiolate redox couple have been investigated; the reaction is chemically reversible but kinetically slow at ambient temperature, which is common to many organodisulphide compounds; oxidation of thiolate occurs via the formation of a thiyl radical which dimerizes in disulphide. Charge transfer is the rate determining step, whereas chemical dimerization is at equilibrium. For the dithiolate, oxidation proceeds in two steps : the dithiolate of the dimer is first formed and is further oxidized to give oligomers. This reaction, in the same manner as for oxidation of the thiolate form, is chemically reversible but kinetically hindered.