The liquid-liquid equilibrium data are presented for ternary mixtures {1-methyl-3-octylimidazoliumchloride (MeOctImCl) + benzene + an alkane} at T = 298.2 K. The alkanes used were heptane, dodecane, and hexadecane. The compositions of the ternary mixtures on the coexistence curve and the conjugate solutions were evaluated using densities and a standard density calibration curve. The solvent MeOctImCl is an ionic liquid, which has a very low vapour pressure and a very high boiling temperature, and is therefore, a potentially environmentally friendly solvent. This 'neoteric' solvent is soluble in water and stable in air. There are very few data in the literature on ternary mixtures involving ionic liquids. The NRTL equation was used to correlate the experimental tie-lines. The NRTL equation gave good correlation of the tie-line data. There are no data in the literature for the mixtures discussed in this paper. The effectiveness of the extraction of benzene from an alkane by MeOctImCl is reported as a ratio of solubilities in the two phases. This quantity, known as the 'selectivity', was found to increase with increasing carbon number of the alkane.