Single crystalline Na2V6O16·2.36H2O nanowires are synthesized by a facile hydrothermal method as a new cathode material for Li-ion battery. The nanowires show a diameter of 60–100nm and a length of up to 5μm. Appropriate thermal treatment could effectively improve the cycling performance, although the discharge capacity is sacrificed to some extent. Na2V6O16·0.86H2O after heat treatment under 300°C delivers an initial specific discharge capacity of 235.2mAhg−1 at 30mAg−1, with a capacity retention of 91.1% after 30 cycles. Long cycling test is demonstrated by the retention of 90.4% and 94.4% at 150 and 300mAg−1, respectively, after 80 cycles. Good rate capability is also achieved for this material. It is proposed that the improved cycling stability of the electrode after thermal treatment is mainly attributed to the removal of a part of crystal water, accompanied with certain structural arrangement.