Liquid-liquid equilibrium (LLE) data for a ternary system water + methyl isobutyl ketone (MIBK) + tert-butyl alcohol (TBA) were experimentally measured at atmospheric pressure over a temperature range of (287.65 to 333.35) K. The consistency of experimental tie-line data has been tested with Othmer-Tobias and Bachman correlations. Binary interaction parameters of NRTL and UNIQUAC models were regressed to correlate the experimental data. It is concluded that UNIQUAC and NRTL equations are reliable to fit the experimental data with the average root-mean-square deviations of 0.87 % and 0.70 %, respectively.