Phase diagrams of aqueous two-phase systems (ATPS) composed of triblock copolymer (F68) 8460 g.mol(-1), sodium sulfate, lithium sulfate, zinc sulfate, or ammonium sulfate were determined at (278 2, 288 2, and 298 2) K The temperature effect on the biphasic area is very small, indicating a strong entropic contribution associating to the phase separation The ability of these four salts in Inducing the formation of the ATPS with F68 followed the order sodium sulfate > zinc sulfate > ammonium sulfate > lithium sulfate.