Liquid-liquid phase equilibria (LLE) of hexyl(2-hydroxyethyl)dimethylammonium tetrafluoroborate (C(6)BF(4)) or hyperbranched polymer (a fatty-acid-modified dendritic polymer, Boltorn U3000) B-U3000 + ethanol + hexane, at T = 298.15 K have been measured. The results are discussed in terms of the selectivity of ethanol and hexane separation. Sloping of the tie lines toward the ethanol vertex is observed for both mixtures (C(6)BF(4) or B-U3000 + ethanol + hexane). The results indicate high selectivity for separation of ethanol and hexane with the ammonium ionic liquid in solvent extraction. The nonrandom two-liquid NRTL model was successfully used to correlate the experimental tie lines. The maximum mean square deviation in mole fraction was 0.01.