Semi-dry flue gas desulfurization was investigated with several kinds of SO2 sorbents, such as slaked lime, limestone, Mg(OH)(2) and concrete pile sludge, in a powder-particle spouted bed. Slurry droplets including sorbent fine particles were fed to a spouted bed of coarse inert particles spouted with hot gas containing SO2. SO2 removal efficiency was strongly affected by the approach to saturation temperature, Ca/S molar ratio and particle size of sorbent. Slaked lime showed the highest desulfurization efficiency. In this process, despite very short gas residence time, more than 90% SO2 removal was easily achieved by choosing appropriate conditions.