Extraction of sunflower oil from sunflower seeds (Heliantus annuus L.) using supercritical CO2 was studied. The shrinking core model was applied to the modeling of the packed-bed extraction process. The experimental data were obtained for extraction conducted at the pressures of 20, 30, 40, 50 and 60 MPa; the temperatures of 313, 333 and 353 K, the CO2 flow rates of 1-4, and 6 cm(3) CO2 min(-1); the mean particle diameters of 0.23, 0.55, 1.09, 2.18 mm. The supercritical CO2 extraction process was modeled by a quasi steady state model as a function of extraction time, pressure, temperature, CO2 flow rate, and particle diameter. The supercritical CO2 extraction process. The intraparticle diffusion coefficient (effective diffusivity) D, was used as adjustable parameter. The model using the best fit of D. was correlated the data satisfactorily. (c) 2005 Elsevier B.V. All rights reserved.