Grape seeds extracts have shown a broad range of pharmacological activities including, among others, antiulcer and antioxidant properties, which are mainly attributed to the phenolic compounds present. To date, the most abundant phenolic compounds isolated from grape seeds are catechins and their derivatives, e.g. quercetin. The present study is devoted to the experimental measurement and thermodynamic modelling of the solubility of quercetin in supercritical CO2 + ethanol as a co-solvent. The solubility of quercetin was measured at 313.15 K, pressures ranging from 80 to 120 bar, and at different content of the modifier ethanol-from 5 to 30%. Two types of thermodynamic models were applied to model the solubility of quercetin-the group contribution equation of state (GC-EoS), developed by Skjold-Jogensen, and the Soave-Redlich-Kwong (SRK) EoS. (C) 2004 Elsevier B.V. All rights reserved.