A reverse flow chromatographic reactor with side feed (RFCR) can be used to improve the conversion and selectivity for irreversible and reversible reaction systems beyond the values obtained from conventional steady-state reactors in the case where the reactants are more strongly adsorbed than the products. It is also simpler than conventional chromatographic, moving, and simulated moving beds and other systems that combine reaction and adsorption separation. The results of the study show the robustness and stability of the system, as well as its capacity to significantly improve conversion and selectivity for several reaction systems, including consecutive reactions. Simulation results of this mathematical model for the hydrogenation of 1,3,5-trymethylbenzene (MES) compare well with previous studies, using countercurrent moving-bed reactors and simulated countercurrent bed reactors. (C) 2004 American Institute of Chemical Engineers.