Vapor liquid equilibrium (VLE) data for one binary system (2-propanol + acetonitrile) and two ternary systems {2-propanol + acetonitrile + 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), 2-propanol + acetonitrile + 1-butyl-3- methylimidazolium tetrafluoroborate ([BMIM][BF4])} were determined at atmospheric pressure (101.3 kPa). It was found that the studied ionic liquids (ILs) both showed a salting-out effect, which leads to the elimination of the azeotropic point, and that the order of separation capacity for imidazolium-based ILs is [EMIM][BF4] > [BMIM][BF4]. All experimental data could be well correlated by nonrandom two-liquid (NRTL) model. (C) 2015 Elsevier B.V. All rights reserved.