Stability constants of the beta-cyclodextrin-dodecyltrimethylammonium complex in water-isopropanol mixtures for compositions between 0 to 34.5 wt% isopropanol were determined by potentiometric measurements. A significant increase in the dissociation constant of the complex was observed when isopropanol was added to its solution in water. Standard Gibbs energies of transfer of the surfactant (DTABr) from water to aqueous mixtures were determined by potentiometric measurements with a junctionless cell. The destabilization of this complex in the presence of alcohol is largely explained by a significant stabilization of the cationic amphiphile.