Hydrodynamic measurements for the spouting of fine particles were obtained In a conical-based cylindrical bed of diameter 0.186 m, inlet orifice diameters of 6 to 14 mm, and included cone angles of 45 to 80 degrees. Four different types of fine particles with diameters ranging from 0.286 to 0.861 mm were investigated. Four different flow regimes-fixed bed, stable spouting, unstable spouting and slugging-were identified and mapped. The termination of the spouting of fine particles was caused by choking rather than by fluidization of particles in the upper bed. Stable spouting could be achieved when the ratio of the orifice diameter to mean particle diameter was less than 20. The measured minimum spouting velocities were within +/-15% of those predicted by the Mathur-Gishler equation. Solids density measurements obtained by a gamma tay densitometer showed that the solid density in the spout increases with bed height and in the annulus is 3% to 10% higher than in a loosely packed bed.