Fe2O3-SiO2 particles, which removes H2S and COS in hot coal gas, are prepared. The characteristics of sulfidation are studied using simulated coal gas from an air blown gasifier. In the temperature range of 623 K to 973 K, the conversion rate of Fe2O3-SiO2 particle to iron sulfide was slowest at 823 K where Fe2SiO4 is formed at reduction before sulfidation. At lower than 823 K, the stable formation is Fe3O4. The conversion rate is of first order in H2S concentration. At more than 823 K. however sulfidation does not proceed in lower H2S concentration than 1,000 ppm-2,500 ppm levels. At temperature 823 K, this concentration is lower than 2,460 ppm, which is higher than the equilibrium concentrations (175 ppm). In the temperature ranges from 673 K to 823 K and from 923 K to 973 K. sulfidation is controlled by pore diffusion under Knudsen diffusion regime. This result shows that sulfidation has the influence of the change of pore radius of Fe2O3-SiO2 particle at reduction.