To determine the kinetics of residue conversion and yields of distillates at very high conversions, bitumen and bitumen fractions were reacted in a 1-L CSTR in a multipass operation. Product from the first pass was collected, then run through the reactor again, and so on. Experiments were conducted both with Ni/Mo on gamma-alumina hydrocracking catalyst and without added catalyst, Products were analyzed by distillation, elemental analysis, microcarbon residue content, and C-13 NMR, The apparent first-order rate constants for residue conversion decreased with increasing level of conversion, once the liquid phase residence time had been corrected for flashing of Liquid product at reactor temperatures. These decreasing rate constants correlated with the fraction of aromatic carbon in the residue fraction, both with and without added catalyst. Sulfur conversion kinetics in the presence of a catalyst were consistent with a simple model for conversion of thiophenic species into sulfides.