Isobaric vapor-liquid equilibrium (VLE) of sec-butyl acetate + para-xylene binary system and methyl acetate + para-xylene + sec-butyl acetate + acetic acid quaternary system were determined at 1013 kPa in a modified Rose still, so as to provide a basis for the design and simulation of the separation process of acetic acid dehydration system. In the present study, the L-W integral test was used to check the thermodynamic consistency of binary VLE data. The results indicated that the thermodynamic consistency of binary VLE data measured in this paper was satisfactory. Furthermore, binary experimental data were correlated well by three models, which are the NRTL, Wilson and UNIQUAC models, respectively. Subsequently, the corresponding binary interaction parameters of each model were obtained. In addition, the NRTL activity coefficient model in combination with Marek-Standart chemical theory was used to predict the quaternary system VLE data for the association of acetic acid. (C) 2015 Elsevier B.V. All rights reserved.