The effect of tetradecyltrimethylammonium bromide (TDTAB) on (1) the reductive electrochemistry of [Co(bpy)(3)](2+) ion to [Co(bpy)(3)](+), and (2) the [Co(bpy)(3)](2+) -mediated electrocatalytic dechlorination of allylchloride has been studied in aqueous 0.1 M KBr solution. TDTAB micellar aggregates strongly stabilise the 1+ complex against chemical decomposition, and also deeply activate it to substantially mediate the electrocatalytic dechlorination of allylchloride. The second order rate constant of the reaction between the micellar bound 1+ complex and allylchloride, estimated by cyclic voltammetry under the conditions of pseudo first order kinetics, however, varies with substrate concentration. Cetyltrimethylammonium bromide (CTAB), on the other hand, gives a uniform value for the second order rate constant. but with reduced catalytic efficiency than TDTAB. The results suggest that the mediated dechlorination reaction is sensitive to the nature of the surfactant aggregates, and emphasise the need for further work on surfactant microstructures and the underlying physical processes.