Liquid-liquid equilibrium data of aqueous two-phase systems (ATPS) formed by mixture of aqueous solutions of triblock copolymer poly(ethylene oxide-b-propylene oxide-b-ethylene oxide), L64, and sulfate salts were obtained. L64 + lithium sulfate + water, L64 + magnesium sulfate + water, L64 + sodium sulfate + water, and L64 + zinc sulfate + water were formed at (278.15, 288.15, and 298.15) K. The influence of temperature in the binodal position was pronounced. The phase separation process was endothermic for the L64 + Li(2)SO(4) system and exothermic for the L64 + MgSO(4), L64 + Na(2)SO(4) and L64 + ZnSO(4) systems. Also, the slope of the tie line tended to increase with an increase in temperature. Also, the capability of the salts to induce the formation of the biphasic system followed the order ZnSO(4) = MgSO(4) > Na(2)SO(4) > Li(2)SO(4).