Abstract: A process for converting hydrocarbon oils into products of lower average molecular weight and lower boiling point comprising contacting a hydrocarbon oil containing less than 200 ppm N at elevated temperature and pressure in the presence of hydrogen with a catalyst A comprising a wide pore zeolite, a binder and at least one hydrogenation component of a Group VI and/or Group VIII metal, wherein the hydrocarbon oil is subsequently, without intermediate separation or liquid recycle, contacted with an amorphous silica-alumina containing catalyst B comprising at least one hydrogenation component of a Group VI and/or Group VIII metal.