[en] Stability is an essential metric of electrocatalysts, but the reported experimental results are often flawed, indicated by the highly inconsistent stability data of the reference catalysts seen in the literature. In this work, focusing on the Pt/C reference catalyst toward the oxygen reduction reaction, we attempted to clarify its genuine stability under the most used accelerated stress test conditions and understand the reasons for the flawed results. Efforts have been made to design an electrochemical cell and an extended test protocol to control all possible experimental factors that could influence the test results. We found that simple experimental errors such as incomplete catalyst activation and accumulated electrolyte impurities could significantly affect the stability test results. Under strictly controlled conditions, a reliable stability benchmark of Pt/C catalyst toward the oxygen reduction reaction has been established. The proposed experimental procedure could serve as a general reference for determining the stability of electrocatalysts for different electrochemical systems.