The electron-transfer kinetics of the ionic surfactant complex cis-chloro/bromo(cetylamine)bis(ethylenediamine)cobalt(III) by iron(II) in aqueous perchlorate medium at μ=1.0 mol·dm-3 ionic strength have been studied at 303, 308 and 313 K by spectrophotometry under pseudo-first-order conditions using an excess of the reductant. The effects of [H+], ionic strength and [Fe2+] on the rate were determined. The reaction was found to be second order and showed to be independence of the acid concentration in the range [H+]=0.05-0.25 mol·dm-3. The second order rate constant increased with surfactant-cobalt(III) concentration and the occurrence of aggregation of the complex itself altered the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe 2+(aq) with the cobal (III) complex proceeds by an inner-sphere mechanism. The critical micelle concentration (CMC) values of these surfactant-metal complexes were obtained in aqueous solution from conductance measurements. Specific conductivity data (at 303, 308 and 313 K) served for the evaluation of the temperature-dependence of the critical micelle concentration (CMC) and the thermodynamics of micellization (ΔG m o,ΔH m o and ΔS m o ). © 2009 Springer Science+Business Media, LLC.