PROCESS OF HYDROCRACKING RESIDUUM CONTAINING PETROLEUM WHEREIN THE METALS WHICH POISON THE HYDROCRACKING CATALYST ARE REMOVED IN A GUARD CASE CONTAINING AN ACID CATALYST ALONG WITH THE ASPHALTENES CONTAINTED IN THE RESIDUUM. THE GUARD CASE CATALYST IS REGENERATED WITH STEAM AND OXYGEN TO MAXIMIZE HYDROGEN PRODUCTION OBTAINABLE BY PARTIAL OXIDATION OF THE ASPHALTENES, AND WHICH HYDROGEN IS THEN USED IN THE HYDROCRACKING PROCESS.