This paper presents an investigation, by discrete method simulation, of particle motion near the walls of fluidized beds. The simulations were performed in two beds, one of 50 mm x 50 mm cross-section, and the other of 90 mm x 90 mm cross-section. The particles used were 0.5 and 1 mm in diameter and 2650 kg/m(3) in density. It was found that the thickness of the down-flowing surface layer is around 15 times the particle diameter. The average downward velocity of particles in the surface layer was found to vary from about 0.01 to 0.2 m/s. Implication of the results in relation to understanding of bed-to-wall heat-transfer in fluidized beds is highlighted. (c) 2005 Elsevier B.V. All rights reserved.