Liquid-liquid (LLE) and liquid-liquid equilibrium (LLLE) data for the ternary system water-acetonitrile-cyclohexene were obtained at 298.15 K and 99.06 kPa. The results of mathematical modelling of LLE and LLLE with the use of the NRTL and UNIFAC models were compared. Both models provide a good description of vapour-liquid equilibrium (VLE). It was determined that the experimental and calculated (NRTL) data are in good agreement, and it was demonstrated that the UNIFAC model could not be used for studying LLE and LLLE in the considered system. (C) 2015 Elsevier B.V. All rights reserved.