A catalyst comprising at least one porous support, at least some platinum, and at least a second group VIII metal which is different from platinum and iridium, said catalyst having been prepared in accordance with a process comprising a) impregnation of the support with at least one solution containing a platinum precursor, b) activation in a neutral or oxidizing atmosphere, at a temperature of between 120 and 800.degree. C., c) activation in a reducing medium, at a temperature of between 0 and 800.degree. C., d1) impregnation with an aqueous solution and d2) treatment with at least one hydrogen donor compound, at a temperature of less than 200.degree. C., e) the impregnation of the support, which has already been impregnated with the platinum, with at least one solution containing a precursor of said second group VIII metal, and f) activation in a neutral, reducing, or oxidizing atmosphere, at a temperature of between 100 and 800.degree. C.