Vapor-liquid equilibria (VLE) for the binary system benzene-cyclohexene and the ternary systems with the ionic liquids 1-hexy1-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [HMIM](+)[BTI](-), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM](+)[BTI](-), N-hexylpyridinium bis (trifluoromethylsulfonyl)imide [HPY](+)[BTI](-), 1-hexy1-3-methylimidazolium tetrafluoroborate [HMIM](+)[BF4](-) and 1-buty1-3-methyimidazolium trifluoromethansulfonate [BMIM](+)[OTF](-) as potential entrainers were measured, to investigate the influence of ionic liquids on the separation factor. The experimental data were compared with the predicted results using mod. UNIFAC( Do). Furthermore activity coefficients at infinite dilution (gamma(infinity)) were measured for benzene in the ionic liquids [HMIM](+)[BF4](-), 1-buty1-3-methylimidazolium tetrafluoroborate [BMIM](+)[BF4](-) and [HPY](+)[BTI](-); for cyclohexene in [HMIM](+)[BF4](-) and [HPY](+)[BTI](-). The gamma(infinity)-values were used to determine the selectivities = at infinite dilution and the capacities k(i) = 1/gamma(infinity) for the system benzene-cyclohexene. Additionally solid-liquid equilibria (SLE) for the system benzene-cyclohexene were measured visually using the synthetic method. The measured SLE data were compared with the results of the group contribution methods UNIFAC and mod. UNIFAC (Do). (C) 2010 Elsevier B.V. All rights reserved.