Steam centrifugation is a mechanical thermal process that decreases the pore liquid in the porous medium by the help of centrifugal pressure and the pressure of injected steam. The steam is used in centrifuges to overcome the capillary forces, which retain the liquid in the lower area of the porous system. Both external forces affect the pore liquid in a different manner. This may lead to a different velocity of the liquid flow and the steam front, resulting in two different states of operation. The steam intrudes the pore and condenses until the bulk is locally heated on boiling temperature. The liquid flow in the porous system can be modeled as a plug flow in a single capillary. The steam intrudes a porous system, which is already partially de-watered, if the acceleration of the pore liquid due to the centrifugal force is more rapid than the penetration velocity of the steam. In this case the pressure difference cannot affect the mechanical de-watering. The pore liquid runs ahead of the condensation front and both processes operate independently. It is intended that the pressurized steam directly acts on the pore liquid and hence interacts with the centrifugal pressure. In this case both external forces are employed to accelerate the liquid in the capillary system and to reduce it to a greater extent. Therefore the relation between steam pressure and centrifugal pressure has to exceed a characteristic value. Then the steam has access to finer pores and finally overcomes the capillary forces. The aim of the experimental and theoretical work is to find the optimal state of operation. Both front velocities can be measured and compared to each other. Furthermore these results are compared to calculations, which can predict the optimal process parameter. With the help of this optimization the steam centrifugation leads to a lower moisture content and operates more economical than a conventional process. (c) 2005 Elsevier B.V. All rights reserved.