Two feeds, a high-metal feed, namely, Boscan heavy crude (BHQ, and a conventional low-metal feed, such as atmospheric residue from Kuwait export crude (KEC-AR), were studied with regard to their capacity to deactivate a hydrodemetallization (HDM) catalyst typically used in Kuwait refineries. Feed properties, such as 1300 wt ppm metal (V + Ni), 10 wt % asphaltenes, and 12 wt% CCR, make BHC an ideal feed to accelerate the deactivation of catalysts in an aging test. The competitive adsorption of coke and metals shortens the lifetime of the HDM catalyst tested in a pilot plant experiment under operating conditions applied in Kuwait refineries by approximate to 80% compared to KEC-AR. During the start of the run phase (up to 240 h), the HDM catalyst accumulated approximate to 6 times more metals and approximate to 1.5 times more coke when aged with BHC instead of KEC-AR. At the end of run, the maximum metal on catalyst (MMOC) in both experiments, accelerated test with BHC (1944 h) and life test with KEC-AR (9720 h), was approximate to 24.5 g of metal (V + Ni)/100 g of fresh HDM catalyst. The coke deposition on catalyst was, however, about 10% higher for the BHC than in the case of KEC-AR. The higher concentration of both total asphaltenes and thermally stable entities (refractory asphaltenes) in BHC could be responsible for its higher coking propensity. The drastic shortening of the life of a HDM catalyst in an aging test with metal-rich feed, such as BHC, is the result of accelerated coking as well as metal poisoning.