An extended investigation of homogeneous fluidization of Geldart's group B solids was conducted in two packed columns (5 and 10 cm OD) whose packing spheres were either 0.41 cm lead shots or 1.1 cm glass beads. Measurements of the main variables that characterize the expansion process of the confined bed provide criteria for choosing the size of the packing spheres, the packing height and the minimum aspect ratio of the bed in order to obtain a regular regime of homogeneous fluidization. This regime is modelled according to a modified form of the Richardson-Zaki's, whose parameters are predicted with good accuracy. (C) 2013 Elsevier B.V. All rights reserved.