The liquid–liquid equilibria (LLE) of ternary mixture (propargyl alcohol+diisopropyl ether+water) were measured under atmospheric pressure and at different temperatures of 297.25, 304.35, 313.15, and 323.25K. It was found that the end points of tie-lines at the four temperatures were located almost on a common solubility curve but the tie-lines possessed different slopes that described different equilibrium relations. A comparison of the predicted values through use of UNIFAC method with the measured LLE data was carried out but the predicted values showed remarkable deviations from the experimental data.