Vapor liquid equilibrium (VLE) data were measured for the ternary system water (1) + ethanol (2) + 1-butyl-3-methylimidazolium chloride ([bmim]Cl) (3). Complete T, x, and y data were obtained in a relatively wide range of ionic liquid (IL) mass fractions up to 0 8 and in a relatively complete composition range for the volatile binary pair The nonrandom two-liquid (NRTL) equation was used for correlation and was revealed to be adequate lot the ternary system in the experimental composition range The ternary VLE behavior was also modeled by the correlation of two data sets, in which the ethanol mole fraction on IL-free basis is respectively at 0 1 and 0 98 In this way. the six data sets were reproduced satisfactorily, with root-mean-square deviations of 0 40 K for temperature and 0.0070 for vapor-phase mole fractions Owing to the regular distribution of the experimental data, a good agreement between the experiment and the calculation was graphically presented The effect of the IL on the VLE behavior of the volatile components was also illustrated.