Experiments on the fluidization of fine particles (Geldart group C) with mean sizes 0.01-18.1 mu m and densities 100-8600 kg/m(3) were conducted. Experimental results show that the process of fluidizing fine particles usually involves plugging, channeling, disrupting, and agglomerating. When fluidized, the entities fluidized generally consist of particle agglomerates varying in size from the largest at the bottom of the bed (some even defluidized) to the smallest at the top (some even unassociated to discrete particles). Best to fluidize are the agglomerates which have reached a uniform equilibrium size after repeated solids circulation. Lowering agglomerate density proves to be an effective measure for improving the fluidization quality of fine particles. The fluidizing behavior of fine-particle agglomerates, compared with that of normal discrete particles, is illustrated diagrammatically. The large amount of factual findings poses a challenging problem for analysis, and even possible quantitative correlation, between particle properties and fluidization behavior.