A Sorbex-type SMB separation instrument was operated for the separation of mixtures of 2-phenyl ethanol and 3-phenyl-1-propanol on a series of eight columns packed with Zorbax C18 bonded silica, using a 60:40 (v/v) solution of methanol and water as the mobile phase. The experiments were carried out with low-concentration mixtures under linear conditions. The elation profiles of both compounds between any two successive columns of the set under steady-state conditions were recorded while compositions of the raffinate and extract were measured. The four safety margin factors, beta(j), were divided into groups : beta(1) and beta(4); beta(2) and beta(3) with different influence. Within the framework of the linear, ideal model of chromatography, a range of flow rates enables an SMB to operate successfully by completely separating the feed into its two components, The influence of different flow rates on the performance of the separator was studied by calculations and experiments with excellent agreement between both sets. With a simple optimization strategy, the four flow rates are selected to maximize the production rate or the concentration of extract and raffinate products, or to minimize the desorbent consumption. These optimum conditions are obtained by controlling the locations of concentration profiles inside the SMB. A reliable model for SMB operation allows a rapid and easy selection of the optimum experimental conditions.