Hydrolysates of lignocellulosic biomass are aqueous solutions containing, among others, sugars and acetic acid. They are concentrated by evaporation. Only little is known on the influence of the sugars on the volatility of the low-molecular-weight components in those mixtures. Therefore, in the present work the isobaric vapor-liquid equilibrium of the systems (acetic acid (M) + water (W) + xylose (X)) and (acetic acid (AA) + water (W) + glucose (G)) was studied at 20.0 kPa in a thin film evaporator. The results show that the volatility of acetic acid is increased by the sugars and that xylose and glucose have a similar influence. The vapor-liquid equilibrium data were correlated using the NRTL model for describing the liquid phase non-ideality and taking the dimerization of acetic acid in the vapor phase into account. (C) 2018 Elsevier B.V. All rights reserved.