Cyclic and ac voltammetry were carried out on 17 different 1,2,3,5-dithia- or diselenadiazole radicals under vacuum in CH2Cl2 and CH3CN solutions containing NBu(4)PF(6) electrolyte. The redox potentials for the oxidation and reduction processes are reported, referenced to SCE using ferrocene as a secondary standard. The oxidation process for five of the dithiadiazole radicals correlates linearly with the gas-phase ionization energies previously obtained from UV-PES, and the damping influence of the solvent medium is evident. Disproportionation energies defined as E(cell) = -{E(oxid) - E(reduc)} were calculated : (E = S, -1.43 +/- 0.06 V in CH3CN and -1.61 +/- 0.06 V in CH2Cl2 (average of 11 compounds); E = Se, -1.25 +/- 0.03 in CH3CN and -1.39 +/- 0.05 V in CH2Cl2 (average of six compounds)) and compared to the enthalpies of the same process in the gas phase obtained from MNDO calculations (E(cell)(gas) = -6.5 V). Both calculation and experiment show that the title compounds, by comparison with TTF+, TCNQ(-), and other related compounds, have higher than desirable disproportionation energies which is a disadvantage for their use in constructing molecular metals. The electrochemistry of 1,4-bis(dithia- and diselenadiazolyl)benzene has also been investigated by voltammetry and coulometry. These bifunctional diradicals undergo independent redox chemistry in each CN(2)E(2) ring, and the "oxidation" process involves a two-electron transfer confirmed by coulometry. The disproportionation energies of these compounds are shown to be similar to those of the monofunctional radicals; by implication the same limitations apply to their solid-state properties.