Mixed systems formed by surfactants, sodium alkylsulfonates, and beta-cyclodextrin have been studied by using the solvolysis of 4-methoxybenzenesulfonil chloride (MBSC) as a chemical probe. The kinetic analysis allows us to obtain the percentage of uncomplexed cyclodextrin in equilibrium with the micellar media and its variation with the alkyl chain length of the surfactant. Competition between surfactant complexation by the cyclodextrin and self-aggregation to form micelles is the driving force for the percentage of uncomplexed cyclodextrin in equilibrium with the micellar system and its variation with the surfactant chain length. (c) 2010 Elsevier B. V. All rights reserved.