The ammoxidation of propane to acrylonitrile was investigated over various multicomponent mixed oxide catalysts. Bi3GaMo2 oxide, Bi0.85V0.55Mo0.4.5 oxide and Bi2TiMo oxide showed a good selectivity to acrylonitrile. The catalytic performance was strongly dependent on the components constituting the oxides due to the concentration of defects, the nature of the component and the mixed oxide phases. The effect of support type on the catalytic performance of Bi0.85V0.55Mo0.45 oxide showed that selectivity to acrylonitrile decreased in the order silica > alumina > magnesia. The catalytic performance of Bi0.85V0.55Mo0.45 oxide was improved by the addition of a small amount of a component such as magnesium, calcium and tellurium. The catalytic performance of Bi3GaMo2 oxide catalyst, however, decreased significantly with the addition of a small amount of alkali metal (Li, Na, K, Cs).