Vapor-liquid equilibria (VLE) and excess enthalpies (H-E) have been measured for the hydrocarbons hexane, 1-hexene, cyclohexane, cyclohexene, benzene and toluene with the ionic liquids 1-metyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [MMIM](+) [(CF3 SO2)(2)N](-), 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [EMIM](+) [(CF3SO2)(2)N](-), 1-butyl-3-methyl-imidazolium bis (trifluoromethylsulfonyl)imide [BMIM](+) [(CF3SO2)(2)N](-), 1-metyl-3-methyl-imidazolium ethylsulfate [EMIM](+) [C2H5OSO3](-) and pyridiniumethoxyethylsulfate [C5H5NH](+) [C2H5OC2H4OSO3](-) at 353.15 K, 303.15 K and 333.15 K, respectively. The experimental VLE and H-E data were correlated together with available activity coefficients at infinite dilution gamma(i)(infinity) using the NRTL and UNIQUAC models and the relative van der Waals volume and surface area parameters r and q estimated by the Bondi method. The overall average errors using NRTL and UNIQUAC model are 4.6% and 4.8% for VLE, 1.7% and 1.9% for gamma(i)(infinity) and 3.6% and 3.2% for H-E. (C) 2004 Elsevier B.V. All rights reserved.