Salient examples of catalytic application of niobium compounds and materials are demonstrated. Niobium oxides, when small amounts are added to known catalysts, markedly enhance catalytic activity and selectivity and prolong catalyst life for various reactions. Moreover, niobium oxides exhibit a pronounced effect as supports of metal or metal oxide catalysts. Hydrated niobium pentoxide (niobic acid, Nb2O5.nH(2)O) and niobium phosphate which are unusual solid acids show high catalytic activity, selectivity, and stability for acid-catalyzed reactions. Layer compounds containing niobium combined with metal show peculiar photocatalytic activity. These characteristic features of niobium compounds as catalysts and catalyst components are discussed, their potential significance being emphasized.