Abstract: The invention provides a nickel/alumina/silicate catalyst, with an atomic ratio of nickel/aluminium between 20 and 2, a nickel/silicate ratio between 20 and 1, an active nickel surface area between 70 and 150 m.sup.2 /g nickel and an average pore size, depending on the above atomic ratio, between 4 and 20 nanometers. Preferably the nickel/aluminium atomic ratio is between 10 and 4 and the nickel/silicate ratio between 12 and 3. Preferably the catalyst has a specific porous structure.The invention also provides a method for preparing the catalyst by a two step process involving precipitating nickel ions and adding during a second, so-called aging step a soluble aluminium compound and optionally the silicate. The silicate is preferably added during a second aging step.The catalyst is useful for hydrogenating unsaturated organic compounds in particular oils.