The KIER bench-scale fluidized hot-gas desulfurization process was designed to operate two different configurations. One was a bubbling desulfurizer and a bubbling regenerator, the other was a transport desulfurizer and a bubbling regenerator. Two systems were compared each other in terms of operational parameters, hydrodynamic parameters such as gas flow rate and solid circulation rate, reaction characteristics such as sorbent sulfur sorption capacity and regeneration characteristics. Also, the fresh and used solid samples from two different modes were analyzed for density, sulfur content, size, attrition, and morphology. The transport-bubbling system was simpler and more stable in pressure balance, but a little more unstable in temperature control than the bubbling-bubbling system. The solid residence time in each reactor was 0.68 h for the bubbling-bubbling system, and 0.09 h for the transport-bubbling system. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.