The adsorption of C-8 isomers (p-xylene, m-xylene, o-xylene and ethylbenzene) was studied under the industrial operating conditions of the Parex process. Single- and multi-component breakthrough experiments were carried out on a Barium exchanged faujasite-type zeolite as adsorbent and p-diethylbenzene as desorbent. Equilibrium isotherms of the main components of the Parex process were obtained from single component breakthrough curves with different feed concentrations in i-octane. A mathematical model is presented which, jointly with the equilibrium experimental data, is capable of satisfactorily predicting the breakthrough curves of multi-component mixtures of xylenes, including the breakthrough curves of the real Parex feed mixture. (C) 2012 Elsevier B.V. All rights reserved.