Searching for environmentally friendly aqueous two-phase systems is imperative for the sustainable development of bioseparation technologies. In the present work, (liquid + liquid) equilibrium data have been determined experimentally for aqueous two-phase systems formed by the cholinium-based ionic liquids (cholinium glycollate, cholinium propionate, cholinium lactate, and choline chloride) and polymers {polypropylene glycol 400 (PPG400), polypropylene glycol 1000 (PPG1000), and poly(ethylene glycol)-block-poly(propylene glycol)-poly(ethylene glycol) (EO10PO90)}. The effects of anion type of the ionic liquids, the nature of the polymers and temperature of the systems are examined on the phase-forming capacity of the systems. Then the binodal results have been satisfactorily fitted to a three-parameter empirical equation. The tie-line data are well described by the Othmer-Tobias and Bancroft equations. (C) 2013 Elsevier Ltd. All rights reserved.