A layered calcium niobate, KCa2Nb3O10, with submicrometer sized particle was prepared by the solid-state reaction of potassium carbonate, calcium oxide, and niobium pentoxide in air at the temperatures of 900 degrees C, which is lower than the reported value (1100 degrees C). The lower temperature synthesis led to better results in the photocatalytic decomposition of methyl orange and the preparation of an aqueous suspension and thin film.