A mathematical model representing m-xylene isomerization reaction and subsequent separation of xylene isomers in a catalytic membrane reactor is proposed. Propylsulfonic acid-functionalized silicalite-1 and arenesulfonic acid-functionalized silicalite-1 membranes were used as the catalytic membranes. A triangular reaction scheme was used as the reaction model while m-xylene conversion, p-xylene selectivity, p-xylene yield, p-xylene flux and p-/o-xylene separation factor under isothermal condition were calculated from the model. The simulated results were analyzed and showed good agreement with the experimental data within an error of +/-5%. The effects of p-xylene diffusivity on m-xylene conversion, p-xylene flux and p-/o-xylene separation factor were investigated. Simulated results showed that the increase in p-xylene flux enhanced m-xylene conversion. p-Xylene yield increased with an increase in m-xylene conversion. m-Xylene conversion by arenesulfonic acid functionalized silicalite-1 membrane was higher compared to that of propylsulfonic acid functionalized silicalite-1 membrane due to higher diffusion rate of p-xylene. The removal of p-xylene through the membrane contributed to higher m-xylene conversion in both of the membranes. (C) 2010 Elsevier B.V. All rights reserved.