Liquid-liquid equilibrium for an aqueous two-phase system containing poly(ethylene glycol) 2000 + potassium citrate + water was studied at three different temperatures of (25, 35, and 45) °C. The binodal curve was fitted to an empirical equation relating the concentrations of PEG 2000 and potassium citrate, and the coefficients were estimated for the respective temperatures. Tie line compositions were correlated using Othmer-Tobias and Bancroft equations, and the parameters are also reported. © 2007 American Chemical Society.