Liquid-liquid equilibrium data for tert-amyl ethyl ether (TAEE) + ethanol + 1-octyl-3-methylimidazolium chloride were measured experimentally at 298.15 K. The experimental data were obtained by direct analysis of phases at equilibrium by H-1 NMR and then correlated using the nonrandom two-liquid equation. The nonrandomness parameter (alpha) was fixed to 0.1, 0.2, and 0.3, and the best results were found with alpha = 0.1. Distribution coefficients and selectivities obtained show that the ionic liquid used can be an excellent extractant agent of ethanol from its mixtures with TAEE, thus allowing ether purification.