Hydrocarbon conversion catalyst

in a hydrocarbon hydroconversion catalyst composition including, on a porous carrier, 0.01 to 5 weight percent of a platinum component selected from the group consisting of platinum metal, platinum oxide, platinum sulfide or platinum halide, or mixtures thereof, 0.01 to 3 percent of a rhenium component selected from the group consisting of rhenium as an aqueous solution of perrhenic acid or ammonium perrhenate, or mixtures thereof, calcining and thereafter heating the catalyst composition in dry hydrogen, and a zinc component taken from the group consisting of zinc metal, zinc oxide, zinc sulfide or mixtures thereof, the improvement comprising, including 0.01 to 0.2 weight percent of said zinc component, calculated as the metal, in said composition.