Micrometer size [10] (N1-xKx)NbO3 (NKN) platelets were synthesized by annealing (K8-8xNa8x)Nb(6)O(19)nH(2)O (KNNH) precursors at 500 degrees C. The plate-like KNNH precursors were produced from (1-y)NaOH-yKOH + Nb2O5 specimens using the hydrothermal process at 160 degrees C. The size of the NKN platelets was similar to that of the KNNH precursor, but the surfaces of the NKN platelets were rough while the KNNH precursor had a smooth surface. The formation of a rough surface is related to the vigorous evaporation of the H2O from the KNNH platelets during the annealing process at high temperatures. NKN platelets with smooth surfaces could be synthesized using KNNH platelets, which were heated to 150 degrees C to evaporate H2O before annealing at 500 degrees C. These NKN platelets can be used for the fabrication of textured NKN ceramics.