Improved processes for the combined desulfurization and hydroconversion of various sulfur-containing pertroleum oils, and particularly various residua feedstocks, are disclosed. These feedstocks are thus contacted with alkali metals, such as sodium, in the molten state, in a conversion zone maintained at specified conditions such that the feedstocks are both desulfurized and subjected to significant hydroconversion, particularly demonstrated by significant reductions in the 1,050.degree. F+ fraction of these feedstocks, as well as significantly decreased Conradson carbon and increased API gravity. In addition, the deep demetallization and moderate denitrogenation of these feedstocks is also achieved. These important results are obtained by maintaining the conversion zone at temperatures of above 750.degree. F, and in the presence of sufficient added hydrogen to produce a hydrogen pressure in the conversion zone of between about 1500 and 3000 psig.