Liquid-liquid equilibrium data for the binary systems water + di-n-butyl phthalate, water + di-ethyl phthalate, and water + di-isobutyl hexahydrophthalate in the temperature range of (298.2 to 348.2) K at normal pressure were determined. The organic compound concentrations in the aqueous phase were measured by the high-performance liquid chromatograph, while the water concentrations in the organic phase were measured by the Karl Fischer equipment. The NRTL and UNIQUAC models, of which the interaction parameters were expressed as a function of the temperature from (298.2 to 348.2) K, were used to correlate the obtained liquid-liquid equilibrium data. The results show that the correlation accuracy of the UNIQUAC model is better than the NRTL model at the studied temperatures.