CANMET is developing a process to simultaneously liquefy coal and upgrade bitumen, heavy oil or petroleum residues. This coprocessing concept is similar to a direct hydroliquefaction process in which the normal coal derived recycle oil is replaced with an externally supplied bitumen or other solvent. Alternatively, it can be viewed as an extension of the CANMET hydrocracking process where much greater coal concentrations are employed in the feed. The net result is a single stage process which combines aspects of both coal liquefaction and heavy oil hydrocracking technologies. At the Synthetic Fuels Research Laboratory of CANMET a continuous bench-scale coprocessing unit has been used to demonstrate the feasibility of the concept using Forestburg subbitumnious C coal from Alberta and Cold Lake vacuum bottoms as solvent. The same coal has also been processed with an anthracene oil solvent to allow direct experimental comparison of product qualities and yields between coprocessing and liquefaction. The characteristics of coprocessing were investigated by changing the major process variables over wide operating ranges including the base case of simple hydrocracking of the solvent. A number of significant trends were observed especially with respect to the effect of coal concentration in the slurry feed. These results are discussed including the nature of potential coal-solvent synergism during coprocessing.