A procedure for estimating equilibrium polymer-water partition coefficients over a broad range of solute hydrophobicity is presented and evaluated. The coefficients were calculated from the concentration change in the liquid phase and hydro-organic mixtures of varying proportions were used to extend the range. Three hydrophobic polymers (PP, PE, and EBA), two types of solvent (acetonitrile and alcohols) and 12 model solutes were used. The estimated polymer-water partition coefficients, log K-pw, ranged from -0.5 to 8.5. The coefficients correlated to other partitioning systems such as the calculated log Poctanol-water up to similar to 14 and the retention factor (log k(w)) in reversed-phase liquid chromatography. (C) 2007 Elsevier Ltd. All rights reserved.