In the present work we report the performance of a Ni-Mo-W/gamma-Al2O3 catalyst in comparison with conventional Ni-Mo and Ni-W catalysts for promoting various reactions that occur during residual oil hydroprocessing. The performance evaluation tests were conducted in a high pressure fixed bed reactor system using Kuwait vacuum residue as feed. The reactions that were monitored included hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodemetallation (HDM), hydroconversion to distillates (HC), asphaltenes removal, and CCR reduction. The results revealed that the Ni-Mo-W catalyst was more active for various conversions than either the Ni-Mo or Ni-W catalyst. The activity improvement was particularly higher for HDN, HDM, HC, asphaltene conversion and CCR reduction. The addition of W to Ni-Mo/Al2O3 enhanced the hydrogenation function of the catalyst.