BACKGROUND: Chromatographic fractionation of concentrated acid lignocellulosic hydrolysates was investigated. The goal was to present a model that can be used in designing and performance evaluation of the fractionation process. Simple models were fitted to the experimental sorption data of the main components of the hydrolysates (sulfuric acid, monosaccharides, and acetic acid) on CS16GC resin. A column model which takes into account resin shrinking was derived. RESULTS: Simulation results were found to be in good agreement with the experimental results. The isotherm models predicted correctly the co-operative effect of H2SO4 on the sorption of the other adsorbates. The effect of column loading on the productivity of the separation process was studied with simulations. With 20 wt% H2SO4, the highest productivity was obtained with 11.5 vol% column loading. In addition, a process consisting of concentrated acid lignocellulose hydrolysis, batchwise chromatographic separation, and H2SO4 recycling was investigated. With the recycling, the maximum productivity was obtained with 18.2 vol% column loading. CONCLUSIONS: It was demonstrated that the entire reactor-separation process with internal recycling must be considered when evaluating the performance of the monosaccharide-acid separation step. Process performance was found to decrease with increasing feed concentration of sulfuric acid. Copyright (c) 2012 Society of Chemical Industry