A hydrocracking study of Athabasca bitumen using a batch reactor with varying concentrations of a microdispersed metal sulfide catalyst (MoS2) in the presence and absence of a common commercial supported catalyst is reported. The work compares the effects of a wide range of MoS2 dispersed catalyst concentrations (0-6000 ppm) on the conversion of residuum and the effects of using that dispersed catalyst with a commercial extruded hydrogenation catalyst. Hydrocracking runs using only the MoS2 microdispersed catalyst showed reduced coke formation only at low Mo concentrations. In the presence of the supported catalyst, solids formation increased significantly and overall catalyst performance was lowered as a function of increased MoS2 microdispersed catalyst concentration.