Ni/Al2O3 catalysts with different weight percentages of nickel (10-50 wt.-%) were prepared by a co-precipitation method under constant and varying pH conditions. Bulk density, pore volume and surface area of the catalysts were measured. The catalysts were characterized by X-ray diffraction. Hydrogen and oxygen chemisorptions were used to measure the metal area, percentage reducibility and metal dispersion. The crystallite size, as calculated from adsorption measurements, is very high. This is explained as being due to poor dispersion. Aniline hydrogenation under vapour phase conditions over these catalysts was studied. Catalysts prepared by the constant pH method show higher activity compared to those prepared by the varying pH method, especially at low metal content, N-phenylcyclohexylamine is the major product. The mechanism of product selectivity under different experimental conditions is explained.