Lignocellulose fractionation is a key biorefinery process that need to be understood. In this work, a comprehensive study on hydrothermal-fractionation of holm oak in a semi-continuous system was conducted. The aim was to develop a physicochemical model in order to reproduce the role of temperature and water flow over the products composition. The experiments involved two sets: at constant flow (6 mL/min) and two different ranges of temperature (140-180 and 240-280 degrees C) and at a constant temperature range (180-260 degrees C) and different flows: 11.0, 15.0 and 27.9 mL/min. From the results, temperature has main influence and flow effect was observed only if soluble compounds were produced. The kinetic model was validated against experimental data, reproducing the total organic carbon profile (e.g. deviation of 33%) and the physicochemical phenomena observed in the process. In the model, it was also considered the variations of molecular weight of each biopolymer, successfully reproducing the biomass cleaving. (C) 2015 Elsevier Ltd. All rights reserved.