Stationary electrode and rotating disc voltammetry studies demonstrate that the electrochemical oxidation of tetrathiofulvalene in aqueous/CTAC micellar solution takes place via two one-electron steps, representing the formation of the mono- and di-cation radicals, respectively. The observed voltammetric wave due to the second oxidation step is, however, anomalously large with respect to that due to the first oxidation step. Diffusion coefficients determined from the observed current vs. potential curves are consistent with the hypothesis that the hydrophilic mono- and di-cation radicals are predominantly solubilized in the aqueous phase and therefore diffuse more rapidly than their hydrophobic and predominantly micelle solubilized parent molecule. For such a system the homogeneous solution reaction between the electrochemically generated dication radical and the neutral reactant species, which leads to the formation of the monocation radical in the diffusion layer, may be expected to have a significant influence upon the mass transport of reduced and oxidized species to and from the electrode surface, and may account for the anomalously large second oxidation wave.