Liquid-liquid equilibrium data are presented for mixtures of 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([C(2)OHmim]BF4) or 1-(2-hydroxyethyl)-2,3-dimethylimidazolium tetrafluoroborate ([C(2)OHdmim]BF4) + water + 1-butanol at 293.15 K. The data presented provide valuable insight into how the environmentally friendly ionic liquid solvent can be used to separate 1-butanol and water. Selectivity values, derived from the tie line data, show that [C(2)OHdmim]BF4 has better extraction capacity than [C(2)OHmim]BF4. The experimental results show that the two ionic liquids are potentially candidates to separate 1-butanol and water by liquid-liquid extraction. The experimental tie lines were correlated with the NTRL equation.