The catalytic performance of some metal oxides in the vapor phase selective oxidation of H2S in the stream containing ammonia and water was investigated. Among the catalysts tested Fe2O3/SiO2 was the most promising catalyst for practical application. It showed higher than 90% H2S conversion and very small amount of SO2 emission over a temperature range of 240~280 ℃. The effects of reaction temperature, O2/H2S ratio, amount of ammonia and water vapor on the catalytic activity of Fe2O3/SiO2 were discussed to better understand the reaction mechanism. The H2S conversion showed a maximum at 260 ℃ and it decreased with increasing temperature over 280 ℃. With an increase of O2/H2S ratio from 0.5 to 4, the conversion was slightly increased, but the selectivity to elemental sulfur was remarkably decreased. The increase of ammonia amount favored the conversion and the selectivity to elemental sulfur with a decrease in SO2 production. The presence of water vapor decreased both the activity and the selectivity to sulfur, but increased the ATS selectivity.