Abstract: The invention relates to a hydrodemetallization process and catalyst, of a sulfur and organometallic containing hydrocarbon feedstock which consists in contacting the feedstock under the usual hydrotreating conditions with a catalyst comprising a refractory mineral carrier composed essentially of a mesoporous alumina with defined characteristics, said catalyst having previously been sulfurized. The process is characterized in that the catalyst contains, in addition to the carrier, in free or combined form, from 0.01 to 0.7 weight percent, based on the total weight of the catalyst, and calculated as if in elemental form, of at least one metal selected from groups Vb, VIb, VIIb and VIII of the periodic table of the elements, so as to give optimum initial demetallizing activity.