TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The carbon content of the catalyst is 0.5-2.6%. The surface area of the support is less than 200 m2/g. The preferred metals from group VI are Mo or W, and from group VIII are Ni or Co.Preparation (claimed): The catalyst is prepared by;(1) impregnation of the metal on a support;(2) an activation step; and(3) deposition of carbon by contacting with a hydrocarbon compound, to deposit 2.8% or less of carbon.The activation stage is effected by contact with a gas containing hydrogen (H2) and hydrogen sulfide (H2S). The carbon deposition is effected during the activation stage. Alternatively, the deposition of carbon may be effected at the same time as the metal impregnation.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Process: The charge for hydrodesulfurization comprises a petrol cut obtained from a catalytic cracking unit, comprising a range from 5C hydrocarbons to compounds of boiling points about 250degreesC. EXAMPLE - Two catalysts based on nickel (Ni) supported on alumina were prepared by dry impregnation of a nickel nitrate solution followed by drying and calcination in air. The activation was carried out by a thermal treatment under H2/H2S/3% cyclohexene (for catalysts 10 and 11), and under H2/H2S for catalyst 9. For each catalyst, the Ni content (as NiO) was 18% and the surface area of the support was 130 m2/g. The carbon contents of catalysts 9, 10 and 11 were, respectively, 0, 0.9% and 5%.    The test charge comprised a synthetic mixture comprising 30% toluene, 1000 ppm of S (as 3-methyl thiophene),10% olefins (as 2,3-dimethyl butene-2) diluted in n-heptane. The reaction was effected at 240degreesC, 2 MPa, H2/HC = 300 l/l and VVH of 8 per hour. The effluents were analyzed by gas liquid chromatography. The activity constants, KHDS, obtained for the catalysts 9, 10 and 11 were 1, 1.03 and 0.92, respectively, and the selectivity, KHDS/KHDO, were 1, 1.28 and 1.10. Thus, a higher selectivity was shown for the pre-coked catalysts 10 and 11. However, catalyst 11 was less active in hydrodesulfurization than catalyst 10, indicating a preference for catalysts containing less than 3% carbon.