The extraction of oil from dittany (Origanum dictamnus) using supercritical carbon dioxide was investigated. The experiments were performed in a bench scale apparatus at the pressures of 100 and 150 bar and at the temperatures of 40 and 60 degrees C. The effect of the solvent flow rate and the mean particle diameter of dittany on the extraction yield was also investigated at 100 bar and 40 degrees C. It is shown that the extraction yield increases with pressure, while the increase of temperature and mean particle diameter leads to the opposite effect. Different flow rates of SCCO2 lead to similar extraction yields. Finally, the overall extraction curves are well correlated by a mass balance model of plug flow, in which the intraparticle diffusion resistance has the controlling role. (C) 2010 Elsevier B.V. All rights reserved.