Densities and viscosities of aqueous solutions of poly(ethylene glycol) 2000 (mass fraction from (5 to 50) %) have been measured at 298.15, 303.15, 308.15, 313.15, and 318.15 K. The density data show a linear variation with mass fraction of the polymer for all temperatures. The viscosity data of PEG 2000 solutions were correlated as a function of mass fraction, using a nonlinear equation, for the five different temperatures covered in the present work. Densities and viscosities of poly(ethylene glycol)-sodium citrate two-phase systems have been measured and are correlated with composition. The tie line lengths (TLL) of the aqueous two-phase systems have also been estimated.