In this study, hydrodynamics such as solid circulation rate and voidage in the desulfurizer and the reaction characteristics of Zn-based solid sorbents were investigated using lab-scale high pressure and high temperature desulfurization process. The continuous HGD (Hot Gas Desulfurization) process consist of a fast fluidized bed type desulfurizer (6.2 m tall pipe of 0.015 m i.d), a bubbling fluidized bed type regenerator (1.6 m tall bed of 0.053 m i.d), a loop-seal and the pressure control valves. The solid circulation rate was measured by varying the slide-gate opening positions, the gas velocities and temperatures of the desulfurizer and the voidage in the desulfurizer was derived by the same way. At the same gas velocities and the same opening positions of the slide gate, the solid circulation rate, which was similar at the temperature of 300 ℃ and 550 ℃, was low at those temperatures compared with a room temperature. The voidage in the desulfurizer showed a fast fluidized bed type when the opening positions of the slide gate were 10~20% while that showed a turbulent fluidized bed type when those of slide gate were 30~40%. The reaction characteristics of Zn-based solid sorbent were investigated by different desulfurization temperatures at 20 atm in the continuous operation. The H2S removal efficiency tended to decrease below the desulfurization temperature of 450 ℃. Thus, the 10 hour continuous operation has been performed at the desulfurization temperature of 500 ℃ in order to maintain the high H2S removal efficiency. During 10 hour continuous operation, the H2S removal efficiency was above 99.99% because the H2S concentration after desulfurization was not detected at the inlet H2S concentration of 5,000 ppmv condition using UV analyzers (Radas2) and the detector tube (GASTEC) which lower detection limit is 1 ppmv.