this work, experimental data of isobaric vapor-liquid equilibria for the ternary system ethanol + water + 1-butyl-3-methylimidazolium chloride ([C(4)mim][ Cl]) and for the corresponding binary systems containing the ionic liquid ( ethanol + [C(4)mim][Cl] and water + [C(4)mim][Cl]) were measured at 101.3 kPa. Vapor-liquid equilibria experimental data of binary and ternary systems were correlated by the NRTL equation. NRTL parameters have been used to predict the evolution of the ethanol-water azeotrope composition with different amounts of ionic liquid.