During the last years, the extraction of biomolecules and chemicals by means of Aqueous Biphasic Systems (ABS) has triggered a renewed interest, making it necessary to characterize fully the solubility data of this kind of system. In this study, two surfactants belonging to Triton X series (Triton X-100 and Triton X-102) are proposed as candidates to form ABS, by adding different potassium-based salts (K3PO4, K2HPO4, K2CO3, K2S2O3 and K2SO3) at T = 298.15 K. Several equations were used to fit the solubility data which were previously obtained by means of the cloud point method. The different phase forming capacities were analyzed in the light of the Hofmeister series, the Effective Excluded Volume (EEV) theory and the molar Gibbs free energy of hydration (Delta(hyd)G). The Othmer-Tobias equation was proposed to correlate the tie-line data. (C) 2012 Elsevier Ltd. All rights reserved.