Activity coefficients at infinite dilution in the temperature range between 303.15K and 353.15K, vapor–liquid equilibria at 353.15K and excess enthalpies at 353.15K of binary systems containing the Ionic Liquids 1-ethyl-3-methyl-imidazolium ethylsulfate [EMIM] + [EtSO 4 ] − , 1-ethyl-3-methyl-imidazolium methylsulfate [EMIM] + [MeSO 4 ] − and 1-ethyl-3-methyl-imidazolium hydrogensulfate [EMIM] + [HSO 4 ] − have been measured. The obtained experimental data are used together with literature data to fit modified UNIFAC interaction parameters between the sulfate anion and the main groups OH and CH 3 OH. The predictions are compared with the experimental values. Additionally an overview about the current status of the modified UNIFAC parameter matrix for Ionic Liquids is given.