Separation of phenylenediamines (PDAs) was attempted using a combination of selective solubilization in an organic solvent and then adsorption from nonaqueous solutions on commercial acidic ion-exchange resins. Toluene was the best solvent for selective solubilization and also for the subsequent sorption of the amines by an acidic ion-exchange resin having sulfonic acid groups on the styrene-divinylbenzene backbone. The equilibrium sorption studies showed very selective sorption of the amines with a high loading capacity on the resin. The uptake of the amines was reinforced by Lewis acid-base interaction between the lone pair of electrons on the nitrogen of the amine and the sulfonic acid group of the resin. In the sorption studies involving mixtures, p-PDA was selectively adsorbed. Molecular mechanics calculations confirm the existence of the acid-base interactions.