Heavy crude oil was upgraded into a lighter oil by means of hydrocracking on an acidic Mo-Ni liquid Catalyst. Upgrading was measured in terms of specific gravity, viscosity, and distillates yield. The experimental results show that heavy crude oil was upgraded to an extent that depends on the severity of the reaction conditions; in all cases the hydro cracked oil was lighter, less viscous, and richer in valuable distillates (up to 60 wt % more) and contained less contaminants,(sulfur-and nitrogen) than the heavy crude oil. Hydrocracking experiments were carried out in a batch reactor that was operated at typical hydrocracking conditions, and the conversion was varied by modifying the reaction time over a range from 30 to 90 min or the reaction temperature from 350 to 450 degrees C, The formation of sediments and toluene-insoluble hydrocarbons increased as the reaction severity and conversion were higher however, the values obtained were small and lower than those Obtained with a commercial heterogeneous catalyst; and in both cases no precipitation was observed. Comparison versus an industrial heterogeneous catalyst under the same reaction conditions indicates that the performance of the liquid catalyst was better in terms of heavy molecules cracking but not as good in terms of contaminant removal.