Hydroconversion processes for converting oil, coal or mixtures thereof are provided utilizing a catalyst prepared by first forming an aqueous solution of phosphomolybdic acid and phosphoric acid at a specified ratio of atoms of P/Mo, and subsequently adding this solution to a hydrocarbon material, followed by heating in the presence of H.sub.2 and/or H.sub.2 S to form a solid molybdenum and phosphorus-containing catalyst.