A downflow-type reactor, or downer, is expected to provide high gas-solid contact efficiency and reaction selectivity. In a catalyst-circulating process, for example, an HS-FCC process, steady upward transportation of catalyst particles using a riser to the top a downer is very important, together with efficient catalyst regeneration. Particle-transport characteristics from a freeboard to the riser were investigated using a fluidized bed with a cone-type freeboard for a variety of experimental conditions of gas flow rate, bed depth, and bed structure. The applicability of this concept to HS-FCC processes is also discussed.