Polyphenol extraction from white grape seeds using supercritical carbon dioxide (SC-CO2) containing different percentages of ethanol-water mixture (57% v/v) as co-solvent was carried out at 40 degrees C. Box-Behnken experimental design was used to optimize the process variables: pressure (80, 100, 120 bar), CO2 flow rate (2,4 and 6 kg/h) and co-solvent percentages (10,15, and 20% (w/w)). Total polyphenols (TPC) and fractionation of proanthocyanidins were determined.The statistically generated optimum extraction conditions to obtain the highest total polyphenol concentration were a pressure of 80 bar, CO2 flow rate of 6 kg/h and 20% (w/w) co-solvent. The value achieved in validation experimental was 7132 mg GAE/100 g DM. Under these operating conditions a good extraction of Fl (>1000 mg catechin/100 g DM) and FII (>800 mg catechin/100 g DM) are obtained. (C) 2017 Elsevier B.V. All rights reserved.