The equilibrium and kinetics of 7-aminocephalosporanic acid (7-ACA) extraction with Aliquat-336 (tricaprylylmethyl ammonium chloride) dissolved in n-butyl acetate as the solvent have been studied over a pH range of 5 to 8. It was found that Aliquat-336 reacts with the dissociated anion of 7-ACA in a stoichiometric ratio of 1:1 and the apparent extraction equilibrium constant, K-P increases with an increase of the aqueous phase pH. The extraction kinetics has been analysed based on the assumption that the interfacial reaction between the 7-ACA anion and the interfacially adsorbed carrier complex controls the extraction rate and the mass transfer resistances of the aqueous and organic phases are unimportant. The role of the interfacial chemical reaction was semiquantitatively assessed from certain measured data on interfacial tension between the aqueous 7-ACA solution and the organic solution of Aliquat-336.