The influence of the liquid saturation degree on the fluid dynamics of the conventional spouted bed coating process is investigated using inert particles such as ABS(R), placebo tablet and glass beads. An aqueous polymeric suspension was used as the coating liquid. The suspension was characterized by its surface tension, density, theology and contact angle between the suspension and the solid surface. The maximum suspension flow rate supported by the bed was determined for these three particles, at operating conditions established by preliminary tests. The solids velocity inside the spouted bed was also measured in order to correlate this circulation rate with the saturation degree of the bed. The fluid dynamics behavior of the bed was analyzed and correlated to the liquid saturation degree as well as particle and suspension characteristics. (C) 2004 Elsevier B.V. All rights reserved.