Chemical structure changes in Cold Lake oil-sand bitumen and catalytic activities of red-mud/sulfur and Ni-Mo catalysts during catalytic hydrotreatment are discussed. Particular attention is given to hydrogenation and hydrogenolysis of structural units, and to the removal of heteroatoms, Ni-Mo catalyst at 450 degrees C reaction temperature gives high conversion of oil-sand bitumen to lower boiling fractions improving H/C ratio and extensive removal of heteroatoms. According to the deposition of metals on the spent catalysts, red-mud/sulfur catalyst is effective for bitumen demetallization, removing V and Ni metals.