The present invention relates to a catalyst of nickel on alumina, a process for obtaining it and use thereof. More specifically, the catalyst has a nickel content between 8 and 30% and it is prepared by means of the impregnation process starting from a shaped support formed by a special alumina having a specific X-ray diffraction pattern, a specific porous structure and acidity. The impregnating solution is formed by an organic nickel salt dissolved in an aqueous solution at a basic pH. This catalyst is useful in diolefin hydrogenation reactions in hydrocarbonated streams.