We report here for the first time the reversible electrochemical lithium insertion in the potassium vanadium bronze K0.5V2O5 leading to LixK0.5V2O5 with 0<x≤1.5. Long and thin platelets of K0.5V2O5 are prepared by a fast and facile synthesis route. A specific capacity of 210 mAh g−1 is available at an average voltage of 2.6V without any significant structural changes even after extended cycling experiments. This vanadium bronze exhibits an excellent capacity retention with still 200 mAh g−1 at C/10 after 70 cycles and a good rate capability with 140 and 120 mAh g−1 at 1C and 1.4C respectively. The electrochemical performance of this cathode material is one of the best among vanadium bronzes.