Atmospheric residue desulfurization (ARDS) is one of the major processes installed in refineries worldwide for upgrading petroleum residues to more-valuable clean products. Because of the importance of the process, research and development related to the process and its associated catalysts has gained increasing attention internationally. Hence, it is necessary to develop a reliable testing methodology for evaluating ARDS catalysts in a relatively short time. From our experience, it has been determined that, within 2-3 months, an ARDS catalyst system consisting of 3-5 catalysts can be evaluated and their performance in an industrial unit can be predicted. This requires generating quality data related to the initial activities, kinetic parameters of individual catalysts, the deactivation behavior, and maximum metal capacity in the catalyst system. Using the proposed catalyst evaluation methodology, values of the apparent reaction kinetics and catalyst life can be determined. These data are fed into an in-house developed mathematical model, which enables the prediction of the performance of the same catalyst system in an industrial scale. Very satisfactory results, from both pilot-plant test and commercial plant prediction, are realized from the developed methodology. When conducting long-life tests using the same feedstock and catalyst system, but under different operation modes, such as the constant-sulfur mode or the constant-temperature mode, the catalyst deactivation behaviors between the two life tests are significantly different, However, their respective values of the maximum metal-on-catalyst (MMOC) of the total catalyst system are very similar.