In many industrial processes, a liquid is spayed right into a fluidized bed. The liquid may then dry, as in fluidized bed dryers and agglomerators, evaporate, as in gas-phase polymerization reactors, or react, as in fluid cokers or catalytic crackers. A liquid injected in a fluidized bed may spread on the bed particles, increasing their cohesivity and reducing the bed fluidity. The liquid may also result in the formation of wet agglomerates that settle at the bottom of the bed. In fluid cokers, it is crucial to prevent agglomeration of wet particles. According to the literature, the liquid viscosity, surface tension and wettability affect the formation of agglomerates. The objective of this work was to determine which liquid properties affect the bed fluidity and the formation of agglomerates. (C) 2004 Elsevier B.V. All rights reserved.