Using a facile and effective method based on the solid phase reaction between Co(OH)2 and KBH4, we successfully synthesize orthorhombic CoB. It is shown that this CoB obtained is of high purity and thermal stability. A possible formation process for orthorhombic CoB is discussed in detail. In addition, crystalline CoB shows excellent electrochemical reversibility and considerable high charge–discharge capacities when it is used as the anode material for nickel-based secondary batteries. The reversible discharge capacities of the CoB electrode are found to be about 380mAhg−1 at a discharge current of 25mAg−1 and 360mAhg−1 at 100mAg−1. Moreover, electrochemical reaction mechanism of CoB is investigated in detail.