A method for converting a hydrocarbonaceous feedstock to a lower boiling product is described which comprises suspending metal-impregnated carbonaceous particles in a reaction zone including hydrogen and the hydrocarbonaceous feedstock at hydrocracking conditions. The metal impregnated on the particles may be sulfided in the reaction zone. The impregnated particles are shown to be surprisingly selective catalysts, and anomalous ranges of particle size and concentration are identified. Methods for preparing the particles are additionally presented.