The (liquid + liquid) equilibrium (LLE) data for two systems containing heptane, toluene, and 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide ([mpim][Tf(2)N]) or 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([amim][Tf(2)N]) ionic liquids (ILs) were determined at T = 313.2 K and atmospheric pressure. The effect of a double bond in an alkyl side chain in the imidazolium cation was evaluated in terms of selectivity and extractive capacity. The results show a decrease of the amount of toluene and heptane dissolved in the IL with the allyl group. Thus, the distribution ratios of toluene and heptane of [mpim][Tf(2)N] IL are higher than those of [amim][Tf(2)N] IL On the other hand, the separation factor of the [amim][Tf(2)N] IL increases comparing to [mpim][Tf(2)N] IL The NRTL model was used to correlate satisfactorily the experimental LLE data for the two studied ternary systems. (C) 2011 Elsevier Ltd. All rights reserved.