N-hexane plays a significant role in the industrial manufacturing process of methanol. The separation of n-hexane and methanol is important and difficult due to the azeotropic phenomenon. The objective of this work is to measure the experimental data for the three ternary systems n-hexane + methanol + ionic liquids (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl), 1-decyl-3-methylimidazolium bis (trifluoromethylsulfonyl)amide and 1-butyl-3-methylimidazolium hexafluorophosphate) at T = 298.15 K and 101.3 kPa. The COSMO-SAC model was used to calculate the infinite dilution activity coefficients of the eleven ILs in the work and in the literature. The liquid-liquid equilibrium data for the ternary systems were compared with the calculated values obtained using the non-random two liquid and universal quasi-chemical activity models, and the binary interaction parameters of the two models were obtained by regressing the experimental data. Comparing the values of the distribution coefficients and separation factors of the three ILs, 1-decyl-3-methylimidazolium bis(trifluoromethylsul fonyl) amide showed the best extraction effect. The influence of the alkyl chain length and different anions on the liquid-liquid equilibrium data was discussed. (C) 2019 Elsevier Ltd.