Improved supported hydroprocessing catalysts, and their method of preparation useful for the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of a petroleum feedstock, including a residuum hydrocarbon feedstock are disclosed. The Catalysts contain at least one Groups VIB metal component, at least one Group VIII metal component, and a phosphorus component, supported on a foraminous support such as alumina. The supported catalysts are characterized by a specific combination of properties, namely, the Group VIII metal to Phosphorous molar ratio, the Group VIII metal to Group VIB metal molar ratio, the phosphorous component to Group VIB component molar ratio and the median pore diameter. The resulting catalysts exhibit enhanced HDN without sacrificing to any significant degree the HDS activity.