Adsorption of monosilane on porous adsorbents consisting of gamma-alumina, alumina-silica, and silica was investigated. The maximum adsorption capacity was observed for alumina adsorbents with drying in nitrogen at similar to 100 degrees C. Thus, monosilane is deduced to react with hydroxyl groups on gamma-alumina surface, although physically adsorbed water interferes with the reaction. On the other hand, hydroxyl groups on silica were inactive for monosilane. The difference in the reactivity of hydroxyl groups with monosilane is ascribed to the basicity of the oxides.