Abstract: The catalytic activity of CoMoS/CNT towards the Egyptian heavy vacuum gas oil hydrotreating was studied. The delivered CNT was functionalized with 6 mol/L HNO₃. The CNT were loaded with 12% MoO₃ (by weight) and 0.7 Co/Mo atomic ratio with impregnation methods. The γ-Al₂O₃catalyst was also prepared by impregnation method to compare both catalysts activities. The analysis tools such XRD, Raman spectroscopy, TEM, and BET were used to characterize the catalysts. The autoclave reactor was used to operate the hydrotreating experiments. The hydrotreating reactions were tested at various operating conditions of temperature 325-375 ℃, pressure 2-6 MPa, time 2-6 h, and catalyst/oil ratio (by weight) of 1:75, 1:33 and 1:10. The results revealed that the CoMoS/CNT was highly efficient for the hydrotreating more than the CoMoS/γ-Al₂O₃. Also, the hydrodesulfurization (HDS) increased with increasing catalyst/oil ratio. Additionally, results showed that the optimum condition was temperature 350 ℃, pressure 4 MPa, catalyst/oil ratio of 1:75 for 2 h. Furthermore, even at low CoMoS/CNT catalyst/oil ratio of 1:75, an acceptable HDS of 77.1% was achieved.