A novel book-like K0.23V2O5 crystal is obtained by a simple hydrothermal method and is explored as a cathode material for Li-ion batteries for the first time. It exhibits a high reversible capacity (of ca. 244 mA h g(-1) at a current density of 50 mA g(-1)), along with a good rate capability (80 mA h g(-1) at a current density of 1800 mA g(-1)) and a good capacity retention (185.3 mA h g(-1) after 100 cycles).