A simple hydrothermal method was used to synthesize crystalline sodium hexaniobate nanorods of high purity in gram quantity by treating Nb2O5 powder in 10 M NaOH at 150 °C without utilizing template molecules. The molecular composition of such material was identified as Na6H2Nb6O19·2H2O. SEM revealed that the majority of these hexaniobate rods had a diameter distribution of 200–450 nm and a length distribution of 40–60 μm, though finer rods with a diameter of 50–100 nm could also be found in the product mixture.