The separation of the nonaqueous azeotropic systems methyl acetate-methanol and ethyl acetate-ethanol was investigated with 13 cations and 27 anions as entrainers to identify suitable ionic liquids using the COSMO-RS model. It is observed that the cations best suited are imidazolium > pyridinium > methyl pyrrolidinium > octyl quinolinium. The lengthening of the alkyl chain of cations was also studied as well as whether the shorter the alkyl chain, the better is the separation. It was also noticed that the efficacy of the anions is in the order [OAc] > [Cl] > [DHP]. It was seen that the influence of anions is more significant on the behavior of ionic liquid solvation in alcohols. The effects of polarity, excess free energy, and excess enthalpy are addressed on nonaqueous systems containing ionic liquids. It is suggested that [EMIM][OAc], [EMIM][Cl], and [EMIM][DHP] can be used as promising entrainers for practical applications of ester-alcohol separation. © 2013 American Chemical Society.