The saturates, aromatics, and resins fractions of maltenes from upgraded oils obtained by slurry-phase hydrocracking (SPH) under low-severity reaction conditions using analytical-grade and mineral catalysts were obtained by chromatographic separation. The reactions in the SPH at low severity with the catalysts used occur by free radicals, and their subsequent hydrogenation is from heavier fractions (asphaltenes and resins) to lighter fractions (aromatics, saturates, and light cuts). The degree of conversion depends on the type of catalyst used (Mo > Fe) and is also proportional to the active metal content of the catalyst. The enhanced conversion of aromatics and resins towards the saturates fraction depends on the hydrogenation capacity of the catalyst. The better flow properties of the maltenes are due to the conversion of heavier to lighter fractions and to the upgrading of the resins fraction properties.