Co–B alloys were synthesized via a chemical reduction method, and adopted as anode materials for alkaline secondary batteries. The structural evolutions and the electrochemical behaviors of the as-prepared Co–B alloys with increasing heat-treating temperatures were analyzed with X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and charge–discharge test. It is found that the Co–B alloys treated at various temperatures show high reversibility. And the electrochemical activities were found to be dependent on the structural evolutions of the Co–B alloys. The amorphous Co–B alloy treated at 50°C achieves an excellent discharge capacity of 304mAh/g in the first cycle, while the Co–B alloy treated at 500°C shows superior cyclicity.