A new homogeneity index is proposed to characterize the fluidization quality of non-slugging fluidized beds of Geldart A particles. The definition of this homogeneity index is based on the comparison of bed expansion between the normal operating condition and an ideal homogeneously fluidized condition. Its value is between zero and unity, representing the worst and best fluidization quality. Compared with other indices of this kind, this homogeneity index has a clear physical definition and is easier to obtain. The ideal bed expansion is derived by a modified Richardson-Zaki equation with the consideration of clusters. In addition, the effects of factors such as bubble diameter, column diameter and fluidization regimes on this homogeneity index are also discussed. (C) 2008 Elsevier B.V. All rights reserved.