The layer structured niobate Cs4Nb6O17•3H2O has been prepared in a solid state reaction using Cs2CO3 and Nb2O5 at 1073 K. Ion exchange reactions of Cs+ in the interlayer space were studied in aqueous solutions. The single phases of lithium, sodium and hydrogen ion exchange products were obtained and they also contained interlayer water. The interlayer water of the lithium ion exchange product was removed by heating at 453 K in a vacuum. The resulting niobate Cs0.26Li3.01H0.73Nb6O17 was evaluated for its use as the cathode in a rechargeable lithium battery. The cathode exhibited discharge and charge capacities of 120 and 110 mAhg-1 for the first cycle in the voltage range of 1.5 – 4.2 V. The amount of Li+ intercalated and deintercalated were 4.0 and 3.6 of the formula unit, respectively.