The aim of this work was to predict the rejection of aroma compounds and permeate flux during the reverse osmosis concentration of model solutions simulating apple juice. For the concentration, the MSCB2521 R99 spiral-wound membrane (Separem SpA, Biella, Italy) was used. The preferential sorption-capillary flow model was employed for this purpose. Water and aqueous solutions of apple juice aroma were used to determine the parameters included in the model. Then, the model was tested with aqueous solutions of glucose and aroma compounds. Experiments were performed at different transmembrane pressures (1.5-3.5 MPa), feed flow rates (200-600 L/h; Reynolds numbers = 51-190), temperatures (15-30 degreesC), and glucose concentrations (9.1-17.0 degrees Brix). Good agreement between experimental and estimated data was observed for most of the aroma compounds and operating conditions used.