For the first time vapor-liquid equilibrium (VLE) data for ternary systems containing ionic liquids are reported. The data were measured by means of a computer-operated static VLE apparatus at 353.15 K with the ionic liquids 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [EMIM](+)[(CF3SO2)(2)N](-) and 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [BMIM](+)[(CF3SO2)(2)N](-) and acetone, 2-propanol and water. The experimental VLE data of the binary systems were correlated using the Wilson. NRTL and UNIQUAC models. The errors using Wilson, NRTL, and UNIQUAC are 3.92%, 1.45%, and 1.53%. The g(E)-model parameters of the binary systems were used to predict the VLE behavior of the ternary systems and the predictions were compared to the experimental datasets. The errors using Wilson-, NRTL-, and UNIQUAC-parameters are 5.61%, 7.22%, and 5.02%. (C) 2004 Elsevier B.V. All rights reserved.