Chain-like and rod-like Co-B nanomaterials are prepared by chemical reduction method in cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) aqueous solution, respectively. XRD patterns demonstrate that the two materials both have amorphous structures. SEM and TEM images show that the chain-like Co-B constructs of one-by-one tactic ball-like particles with nanoflakes on the surface, whereas the rod-like Co-B alloy possesses a porous nanostructure. The results of electrochemical measurements indicate that, as negative electrode materials of Ni-MH batteries, their electrochemical properties are both better than those of regular Co-B alloy. At the discharge current density 25mAg−1, the discharge capacities of the chain-like and the rod-like Co-B alloys are 314mAhg−1 and 292mAhg−1 after 50 cycles, respectively, which are both higher than that of regular Co-B alloy. XRD patterns of the electrodes on different charge–discharge states illustrate that the discharge capacity is attributed to hydrogenation of Co-B alloy.