Vapor-liquid equilibrium (VLE) data for water + 2-propanol + 1-butyl-3-methylimidazolium chloride ([bmim]Cl) were measured. Six sets of complete T

x

y data are reported

in which the 2-propanol mole fraction on IL-free basis is fixed separately at 0.1

0.2

0.4

0.6

0.8

and approximate 0.98

while the IL mass fraction is varied from 0.1 to 0.8

in an interval of 0.1. The non-random-two-liquid (NRTL) and electrolyte non-random-two-liquid (eNRTL) equations are used to correlate the experimental data with satisfactory results. The ternary VLE behavior is also modeled with the parameters obtained by correlating two data sets

in which the mole fraction of 2-propanol on IL-free basis is approximately 0.1 and 0.98. In this way

the six sets of data are reproduced satisfactorily. With the eNRTL model

the root-mean-square deviation for temperature is 0.82 K and that for vapor-phase mole fraction is 0.0078. The influences of IL on activity coefficients and relative volatility of the volatile components are also graphically illustrated.