The (liquid + liquid) equilibrium for the {polyethylene glycol dimethyl ether 2000 (PEGDME(2000)) + di-sodium hydrogen citrate + H2O} system was studied at T = (298.15, 308.15 and 318.15) K and atmospheric pressure (approximate to 85 kPa). The free energies, enthalpies and entropies of cloud points were calculated in order to investigate the driving force formation of this two-phase system. To investigate the effect of molar mass of the polymer on the binodals and tie-lines, similar measurements were also made at T = 298.15 K on this two-phase system consisting of the PEGDME with molar masses of 500 and 250 g . mol(-1). The effective excluded volume model was used for representation of the phase-forming ability in PEGDME systems. An empirical and the Merchuck equations with the temperature dependency were used to correlate the binodal curves. The Othmer-Tobias and Bancraft and Setschenow equations, the osmotic virial and the extended NRTL models were used to fit the tie-line data. (C) 2015 Elsevier Ltd. All rights reserved.