Ni-B nanospheres were synthesized through chemical reduction of nickel ions with borohydride in an emulsion system comprised of cyclohexylamine, polyethylene glycol, and water. With the characterization of X-ray diffraction, selective area electronic diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, the resulting hollow Ni-B nanospheres were identified to be amorphous alloys with a hollow chamber. Cyclohexylamine played a significant role in fabricating hollow Ni-B nanospheres, because only solid nanoparticles were obtained in the absence of cyclohexylamine. Polyethylene glycol also had a significant influence on the formation of hollow Ni-B nanospheres, because low yield of hollow nanospheres were achieved without this polymer. During liquid-phase chloronitrobenzene hydrogenation, the as-synthesized Ni-B catalyst exhibited a much higher activity and even better selectivity than the dense Ni-B nanoparticles prepared by direct reduction of nickel ions with borohydride.