Abstract: A method for converting a hydrocarbonaceous feedstock to a lower boiling temperature product is described which comprises suspending metal sulfide particles and oxide particles in a reaction zone including hydrogen and the hydrocarbonaceous feedstock at hydrocracking conditions. The metal sulfide particles and the oxide particles are introduced into the reaction zone through particle precursor fluids which precipitate upon heating to form the particles. The metal sulfide particles contain sulfidable transition metals. The oxide particles contain oxidizable elements such as magnesium, aluminum, silicon, phosphorous, calcium, scandium, titanium, gallium, germanium, zirconium, cerium, and mixtures thereof and are not hydrogenation catalysts under the reactor conditions. The oxide particles resist being chemically reduced by reducing agents in the reaction zone. Surprisingly, the presence of the oxide particles is associated with a significant reduction of coke production in the reaction zone.