A theoretical model for bubble breakup in slurry bubble columns as well as three-phase fluidized beds with fine particles has been developed based on an exploration into the deformation, oscillation and breakup process of the bubbles. The time response of the bubble to the bombarding eddy is taken into account, and as a result, the influence of the dispersed phase density and the operating pressure can be included in the model. The solids and the liquid phase are treated as a homogeneous mixture and the effect of solid concentration on turbulent properties is considered. The relationship between daughter size distribution and turbulent eddy size was established. The model predicts the tendency of decreasing bubble diameter under elevated pressure correctly. (c) 2006 Elsevier Ltd. All rights reserved.