Disclosed are a process and an installation for treatment of a heavy petroleum feedstock, of which at least 80% by weight has a boiling point of greater than 340° C., wherein the process includes (a) hydroconversion in a boiling-bed reactor operating with a rising flow of liquid producing a hydroconversion effluent; (b) separation of hydroconversion effluent into a gas containing hydrogen and H2S, a fraction comprising gas oil, and a naphtha fraction; c) hydrotreatment, by contact with at least one catalyst, of at least said fraction comprising gas oil, producing a hydrotreatment effluent; and d) separation of hydrotreatment effluent into a gas containing hydrogen and at least one gas oil fraction having a sulfur content of less than 50 ppm, wherein the hydrogen supply for the hydroconversion and hydrotreatment is delivered by a single compression system.