In the upgrading of heavy petroleum oils and residues by hydrotreatment, multiple-reactor fixed-bed units loaded with different types of catalysts are used extensively. Catalysts for such hydrotreatment processes are chosen on the basis of activity, selectivity, and life. The performance of the overall hydrotreatment process, with regard to various reactions, such as hydrodesulfarization (HDS), hydrodenitrogenation (HDN), hydrodemetallization (HDM), asphaltenes cracking (HDAsph), and conversion to distillates, as well as catalyst life-on-stream, are clearly linked to the performance of the catalyst in different reactors. Information regarding the activity, selectivity, kinetic parameters, and deactivation of the individual catalysts are, therefore, highly desirable for optimizing reactor loading in the multiple-catalyst system. This paper presents the performance tests for various reactions on two types of industrial hydrotreating catalysts: those used at the midsection and the tail-end of a graded catalyst system designed to hydrotreat atmospheric residual oils. The tests were conducted using straight-run Kuwait atmospheric residue, a demetallized residue, and a demetallized/desulfurized residue. The activity and kinetic parameters for different reactions that are typically occurring during the hydroprocessing of these feedstocks were determined. The results revealed significant changes in activity, depending on the feedstock used for the tests. Furthermore, apparent rate orders and rate constants for some reactions were significantly changed. The study demonstrates the importance of proper selection of the feedstocks used in the performance evaluation and screening of candidate catalysts for graded catalyst systems for residual-oil hydrotreatment.