In past few decades, a strong attention is paid to develop high-active catalysts for hydrotreating of the heavy vacuum gas oil (HVGO). In an agreement with that claim, this research work reports the synthesis of a developed catalyst for desulfurization of a petroleum HVGO fraction. Particularly, the catalytic performance of the catalyst, which was made via addition of CeO2 to ɣ alumina as supports for a trimetallic composite (CoNiMo-Al2O3), toward sulfur removal was investigated. For proper comparison, the activity of alumina individually-supported trimetallic catalyst CoNiMo-ɣAl2O3 at such application was also studied. The as-prepared catalysts were characterized by N2 physical adsorption/desorption (BET), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Catalytic activity was conducted in continuous flow trickle-bed reactor at various operating condition of temperature (320-380 °C), pressure (20-60 bar) and liquid hour space velocity (1-2.5 h-1). It was found that CoNiMo/CeO2-ɣAl2O3 was of a higher catalytic efficiency to hydrotreating of HVGO than that of CoNiMo-Al2O3. Numerically, CoNiMo/CeO2-ɣAl2O3 could successfully remove 83.5 % of sulfur compounds while it was only 66.2% in case of CoNiMo-Al2O3. The increased catalytic performance of ceria containing composite may be due to its high specific surface area (∼198.4 m2·g−1) and small crystallite size (24.24 nm). Moreover, the incorporation of CeO2 to alumina could subsequently inhibit the interaction between Ni and alumina; hence the inactive NiAl2O4 phase had not been formed. Thus, an enhanced catalytic desulfurization process could be attained.