Selectivity coefficients for the exchange of benzoate, 2-, 3-, and 4-hydroxybenzoate with bromide at the air/solution interface have been measured by ion flotation, using the surfactant tetradecyltrimethylammonium bromide. The selective binding of these ions at the interfaces were found to be in the order 2-hydroxybenzoate (salicylate) > 3-hydroxybenzoate > benzoate > 4-hydroxybenzoate > bromide. The standard free energy changes calculated from the selectivity coefficient are consistent with results for micelles. Selectivity coefficients were measured for 2-hydroxybenzoate at different temperatures, from which the enthalpy and entropy changes for exchange were calculated. It was found that the binding is mainly driven by enthalpy and that consequently temperature has little effect on the selective uptake of salicylate.