The effect of temperature on the liquid-liquid equilibrium for the aqueous two-phase system containing poly(ethylene glycol) 2000 + sodium citrate + water was studied at (25, 30, 35, 40, and 45) degrees C. An equation for the binodal curves was obtained in terms of the concentrations of PEG 2000 and sodium citrate, and the temperature effect was also incorporated into the equation parameters. The tie lines were correlated using the Othmer-Tobias and Bancraft equations as well as osmotic virial equation. The mean deviations between the experimental and calculated equilibrium compositions in the top and bottom phases were < 1 %.