A catalyst prepared by the steps which comprise: (a) adding to an asphaltene-containing hydrocarbonaceous oil charge stock a heteropoly acid and a sulfide or a salt of a metal selected from Group IV through Group VIII and mixtures thereof and water; (b) converting the heteropoly acid and metal within the charge stock by heating the oil to a temperature from about 120.degree. F. (43.degree. C.) to about 500.degree. F. (260.degree. C.) to produce at least one organometallic compound within the charge stock; and (c) converting the organometallic compound within the charge stock under hydroconversion conditions including a temperature from about 650.degree. F. (343.degree. C.) to about 1000.degree. F. (538.degree. C.), a hydrogen partial pressure from about 500 psig (3448 kPa gauge) to about 5000 psig (34475 kPa gauge), and a space velocity from about 0.1 to about 10 volumes of oil feed per hour per volume of reactor to produce the catalyst.