Oil sands derived heavy crude oil also known as synthetic crude is emerging as an alternative. source of feedstock to the refiners for producing transportation fuels. The presence of very high levels of sulfur and nitrogen in these heavy gas oils needs to be reduced before they are used for further processing. This at present is accomplished by hydrotreating these stocks over Ni-Mo based alumina catalysts at high temperature and pressure. During hydrotreatment of oil sand derived heavy gas oil, residual fraction (500 degreesC+) is converted into more valuable gasoline and middle distillate range products. The effect of different process variables on the conversion of residual fraction (500 degreesC+) of heavy gas oil has been studied in a trickle bed reactor using 5 mL of alumina supported Ni-Mo based commercial catalyst. The process variables studied were temperature (365-415 degreesC), liquid hourly space velocity (0.5-1.9 h(-1)), pressure (65-88 bar), and hydrogen/heavy gas oil volumetric ratio (400-1000 mL/mL). The effect of all these variables on the conversion of microcarbon residue (MCR) has also been investigated: It was found that significant reduction in the residual fraction and MCR content of the heavy gas oil can be achieved by selecting appropriate hydrotreatment conditions. The kinetics of the removal of residual fraction and MCR content as well as the generation of more valuable distillate products has also been studied in this work, Power law models having order of reaction equal to 2.0 can be used to describe the kinetics of the removal of residual fraction and the MCR content.