Vapor-liquid equilibria (VLE) for the binary systems benzene-cyclohexane, 1-hexene-n-hexane and 2-propanol-water and the ternary systems with the ionic liquids 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [HMIM](+)[BTI](-) and 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [BMPYR](+)[BTI](-) as entrainers were measured, to investigate the influence of ionic liquids on the separation factors. The experimental data were compared with the predicted results using mod. UNIFAC (Do). The predicted results are in good agreement with the experimental data. (C) 2009 Elsevier B.V. All rights reserved.