Abstract: A hydrofining process in which a sulfur- and hydrocarbon-containing processing stream is supplied to a multi-stage hydrotreating reactor incorporating separate stages of cobalt molybdenum catalysts. Hydrogen may be supplied concurrently or counter-currently with the hydrocarbon-containing processing stream. The processing stream is passed into contact with an initial catalyst stage comprising a cobalt molybdenum desulfurization catalyst present in a minor amount of the total composite amount of catalysts within the reactor. Thereafter the processing stream is passed through a subsequent catalyst stage comprising a major amount of cobalt molybdenum hydrocracking catalyst. The effluent stream having a reduced sulfur content is then withdrawn from the hydrotreating reactor. The initial and subsequent catalyst stages are separated by an intervening sector within the reactor containing an inert particulate refractory material, specifically silica particles generally spheroidal in shape.