Phase equilibria of an aqueous two-phase system consisting of polyethylene glycol (PEG 2000) + triammonium citrate + water were determined at different temperatures (298.15, 308.15, and 318.15) K. The binodal curve moves toward the origin with an increase in temperature, resulting in an increase in the two-phase region with an increase in temperature. The effective excluded volume (EEV) of the above aqueous two-phase system was determined from the binodal data. The salting-out capacity of the system increases with the temperature and is explained by the increase of EEV with increase in temperature. The effect of PEG molecular weight, cation, and anion on the binodal curve was analyzed using EEV, Gibbs free energy of hydration (Delta G(hyd)), size of cation, and type of anions. The phase equilibrium compositions, tie-line length (TLL), and slope of tie-line (STL) were determined at (298.15, 308.15, and 318.15) K. The consistencies of the experimental equilibrium data were explained with the Othmer-Tobias and Bancroft equations. The salting-out coefficients were determined from tie-line compositions using Setschenow equation. The salting-out coefficient increases with the increase in temperature.