The objective of this work was to examine the thermodynamics of a coupled process in which ion-pair extraction and adsorption are coupled for the separation of anionic solutes from aqueous solutions. In this work, we used a hydrophobic quaternary ammonium chloride extractant (Aliquat 336) and an acrylic ester sorbent (XAD-7) and studied the selective separation of benzenesulfonate from benzoate. The ion-pair extraction step was observed to be slightly endothermic with enthalpies of +4.0 and +3.3 kcal/mol for the benzenesulfonate and the benzoate ion pairs, respectively. Adsorption of the ion pairs from the organic liquid was observed to be exothermic with enthalpies of -12 and -9 kcal/mol for benzenesulfonate and benzoate, respectively. As expected from the contribution of the individual steps, the coupled process of ion-pair extraction and adsorption was observed to be exothermic. When aqueous mixtures of benzenesulfonate and benzoate were separated by the coupling of ion-pair extraction with adsorption, affinity measurements indicated Delta Delta G degrees values of only -0.9 kcal/mol despite Delta Delta H degrees values of -2.1 kcal/mol.