Acetone-butanol-ethanol (A-B-E) fermentation is the most common way to produce biobutanol. This valuable product may be removed from the fermentation broth by extraction using a convenient hydrophobic solVent such as ionic liquid, which is suggested in this study. A proper design of the extraction unit requires an experimentally validated model of thermodynamic liquid-liquid equilibrium in the two-phase mixture containing all components of the aqueous fermentation broth and extracting solvent. Here, for modeling of LLE, the NRTL model was employed. The equation parameters were determined from data measured for three hydrophobic ionic liquids: 1-buty1-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Bmim][Tf2N], 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6], and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide [Bmp][Tf2N]. (C) 2014 Elsevier B.V. All rights reserved.