Isothermal vapor-liquid equilibria for the ternary system {ethyl tert-butyl ether (ETBE) + ethanol + trihexyltetradecylphosphonium chloride ([P-666,P-14][Cl]) or trihexyltetradecylphosphonium bis(2,2,4-trimethylpentyl)phosphinate ([P-666,P-14][TMPP])} have been determined at 313.15 K using headspace gas chromatography (HSGC). The addition of a small amount of ionic liquids (ILs) to the system ETBE + ethanol produced an important salting-out effect. The azeotrope disappeared by varying the mole fraction of ILs from 0.05 to 0.10. The experimental VLE data were correlated using the Wilson equation. In addition, excess molar volumes (V-E) and deviations in molar refractivity ((R) data at 298.151< are reported for the binary systems {ETBE + [P-666,P-14][Cl]} {ETBE + [P-666,P-14][TMPP]}, and {ethanol + [P-666,P-14][TMPP]} by a digital vibrating tube densimeter and a precision digital refractometer. The V-E and (R were well correlated according to the Redlich-Kister equation. (C) 2013 Elsevier B.V. All rights reserved.