The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought to play an important role for effective conversion of heavy hydrocarbon compounds into lighter fractions restricting carbon formation. The performance of the AC catalyst was exaimined by continuous hydrocracking by CSTR for the removal of such impurities as sulfur and heavy metals (nickel and vanadium), which are mostly concentrated in the asphaltenes. The AC catalyst was confirmed to be very effective for the removal of heavy metals from Middle Eastern VR, Maya/Istmo VR and Maya VR. The extruded AC catalysts were produced by industrial manufacturing method. The application test of the extruded AC catalyst for ebullating-bed reactor as one of the commercially applicable reactors was carried out at the ebullating-bed pilot plant for 500 h. The ebullition of the extruded AC catalyst was successfully traced and confirmed by existing gamma-ray density meter. The extruded AC catalyst showed stable performance with less sediment formation at an equivalent conversion by conventional alumina catalyst at commercial ebullating-bed unit. The degradation of the AC catalyst at the aging test was observed to be less than that of the conventional alumina catalyst. Thus, the AC catalyst was confirmed to be effective and suitable for upgrading of heavy oil, especially such heavy oils as Maya, which contains much heavy metals. (C) 2004 Elsevier B.V. All rights reserved.