Here we report on a study using a simulation of fluidized beds of spherical particles whose size and density place them in Group A of Geldart's classification. The 2D soft-sphere discrete element method simulations use up to 106,400 particles, giving bed dimensions of the order of several centimetres. Simulations have been performed in the absence of any interparticle cohesive force and with an imposed cohesive force equivalent in magnitude to several times the single particle weight. Homogeneous fluidization is observed for a significant range of gas velocity and minimum bubbling velocity is found to be greater then minimum fluidization velocity, even when there is no interparticle force. This is evidence of true Group A behaviour in the absence of interparticle cohesive force. Smaller particles, further from the boundary between Groups A and B, showed more expansion before the start of bubbling and a higher ratio of minimum bubbling velocity to minimum fluidization velocity. (c) 2005 Elsevier B.V. All rights reserved.