Abstract: This invention relates to novel catalysts, of two distinct types, useful for the catalytic hydroconversion of the 1050.degree.F.+ hydrocarbon material contained in heavy crudes and residua such that the resulting product will be suitable for further processing in conventional refinery operations allowing maximization of clean liquid products. Catalysts, which include Group VIB and Group VIII metals, preferably in admixture, and preferably including a Group IVA metal, notably germanium, having certain critical ranges of physical characteristics inclusive of large uniform pore sizes, are used for the conversion, these having been shown to possess improved catalytic activity and selectivity for the hydroconversion of the 1050.degree.F.+ materials of the heavy feeds and residua. Novel methods are described for the preparation of such catalysts, as well as for use of such catalysts. One of the catalysts, i.e.

Abstract: The maximum conversion and desulfurization of residual petroleum oils having a high content of asphaltenes can be attained by first converting a maximum amount of the asphaltenes contained in these feeds by pretreating the feeds with hydrogen under a selected combination of operating conditions. Conditions of temperature between 700.degree. and 800.degree.F, liquid space velocity between 0.1 and 2.0 V.sub.f /hr/V.sub.r and hydrogen partial pressure between 1200 and 3000 psig, result in a maximum conversion of asphaltenes when 5 to 45 volume percent of the 975.degree.F+ fraction in the feedstock is converted to lower boiling fractions.