Phase diagrams of aqueous two-phase systems composed of N-butyl-pyridinium nitrate + salt (ammonium sulfate and sodium sulfate) + water determined at (298.15, 308.15, 318.15 and 328.15) K. The binodal curves were associated with the Merchuk expression and another two empirical expressions. The influences of temperature and the type of cations were also studied, which demonstrated that lower temperature led to the expansion of the two-phase region, whereas the salting -out abilities of Na2SO4 exceeded that of (NH4)(2)SO4) which was proven by the Gibbs free energy of hydration of the ions.