The reaction methyl 4-nitrobenzenesulfonate + Br- was studied in tetradecyltrimethylammonium bromide aqueous solutions in the presence and absence of 0.1 M NaBr, as well as in N-tetradecyl-NiV-dimethyl-3-ammonio-1-propanesulfonate (SB3-14) micellar solutions in the presence of 0.1 M NaBr. Discussion of kinetic results in cationic micellar solutions was used to show some problems concerning the estimation of the second-order rate constants in the micellar pseudophases. The errors introduced by rationalizing the kinetic micellar effects in SB3-14 micellar solutions through pseudo-first-order rate constants were also shown; the contribution of the reaction occurring in the aqueous phase and the binding of the bromide ions to the sulfobetaine micelles were the cause of such errors. To complete the work, the influence of the cation coming from the added bromides on the micellar effects observed in SB3-14 micellar solutions was investigated. Results give information about how cations influence the bromide association to the SB3-14 micellar aggregates.