Hot coal syngas desulfurization with metal oxides in the integrated gasification combined cycle (IGCC) has the potential to improve the economic benefits [1]. Coal syngas contains not only hydrogen sulfide (H2S) but also other sulfurous gases including carbonyl sulfide (COS). In comparison to H2S, COS is more difficult to remove due to its low reactivity with metal oxides. Therefore, the formation of COS in hot syngas will lower the hot syngas desulfurization efficiency. To overcome this limitation, studies of COS removal by sorption, catalytic hydrolysis and hydrogenation conversion have been reported. Among the COS removal technologies, indirect removal by COS conversion reaction and H2S removal is more attractive due to the high removal efficiency [2].