Nickel nanoparticles supported on boehmite were prepared by a modified electroless nickel-plating method and a direct reduction method. We mainly studied the catalyst synthesized by the direct reduction method. The as-prepared nickel catalyst was characterized by X-ray diffraction and high-resolution transmission electron microscopy. The catalytic behavior in selective hydrogenation of p-nitrophenol to p-aminophenol and p-chloronitrobenzene to p-chloroaniline was studied and compared with Ni-B/gamma-Al2O3 catalyst prepared by incipient-wetness impregnation and Ni-B/Al2O3 center dot xH(2)O catalyst synthesized by a coprecipitation method. The Ni-B/boehmite catalysts were found to be more reactive than the Ni-B/gamma-Al2O3 and Ni-B/Al2O3 center dot xH(2)O catalysts. The superior activity of the Ni-B/boehmite catalyst was attributed to the small Ni-B particles and large amount of structural water, which enhanced the hydrophilicity of the catalyst.