In this work experimental results of sunflower seed oil extraction using supercritical CO2 are presented, together with the outcome obtained by applying to the same data a theoretical model recently developed and further improved here. We performed extraction tests utilizing a supercritical extraction equipment having a volumetric capability of 100ml: the seeds were milled to obtain different particle sizes (mean diameter between 0.19 and 1.2 mm): the range of pressure investigated was 280-550 bar, the temperature and solvent flow rate were maintained constant at about 40 degrees C and 10 g/min, respectively. The model accounts for the distinction between broken and intact oil-bearing cells and describes the extraction kinetics similar to the shrinking core models: it allowed satisfactory fitting of the experimental data and permitted to calculate the effective diffusivity of the oil in the seed, which resulted equal to 3 x 10(-11) m(2)/s. The reliability of the model is demonstrated by the fact that the value of the effective diffusivity, resulting from model optimization procedures, is similar for the various experimental tests. (C) 2009 Elsevier B.V. All rights reserved.