This work presents a dynamic transport model of a solid-liquid media through a twin-screw extruder (TSE). The application under consideration is the solid-liquid extraction of solute from raw plant substrate. Dynamic experiments are performed and compared with the simulated results for step functions on the solid feed rate and on the screw rotating speed. Despite some imperfections, results allow to validate the simulator. (C) 2003 Elsevier B.V. All rights reserved.