The group-contribution with association equation of state (GCA-EoS) is applied to represent high-pressure phase equilibria in mixtures of supercritical gases (carbon dioxide, propane) with fatty oil derivatives, such as mono- and di-glycerides, fatty acids and fatty acid esters. Association effects in these mixtures are described by a group-contribution approach using three different association groups: the hydroxyl group, the acid group and the ester group. Satisfactory predictions of vapor-liquid equilibria, liquid-liquid equilibria and gamma infinity of binary and ternary mixtures of high-molecular weight triacyglycerides and their derivatives with carbon dioxide or propane are obtained. It is shown that the GCA-EoS is a powerful engineering tool for the design and optimization of extraction and fractionation processes of fatty oil derivatives with supercritical fluids. (c) 2004 Elsevier Ltd. All rights reserved.