In the present study, both A-activated analogues performed significantly worse in 50 cm 2 MEAs, experienced a higher amount of less noble metal dissolution and most importantly, exhibited a larger shift in the potential of the CO-electrooxidation peak maximum. Thus, a much simpler and more accessible technique like TF-RDE as a rather precise and very sensitive preliminary indicator (via CO-electrooxidation) that can help distinguish between a 'poorly' or 'adequately' de-alloyed (activated) Pt-alloy electrocatalyst. On the other hand, also following the protocols used in this study, one can gain insights on the chemical activation in relation to the less noble metal dissolution using the EFC-ICP-MS. Furthermore, evaluating Pt-alloy electrocatalysts in single-cells at a lower RH (hot-dry) as well as in air rather than in O2 reveals significantly more information about the performance of Pt-alloy electrocatalyst performance than at high RH (hot-wet). Overall, it is clearly presented that the presence of the less noble metal ions in the CCM is one of the most critical parameters governing the performance of Ptalloys. relation to the less noble metal dissolution. Thus, better understanding of Pt-oxide formation and reduction in relation to Pt dissolution as well as subsequent dissolution of the less noble metal is crucial to enable the use of Pt-alloy cathodes at HCDs needed for automotive conditions. We show that operating Pt-alloys below 0.7 V results in a significantly higher degree of less noble metal dissolution and thus, higher voltage losses when using Pt-alloy cathodes in single-cells even at relatively low UVLs/UPLs of 0.925 V. In addition, we have discovered that oxide place exchange responsible for Pt cathodic transient dissolution plays a crucial role in this. Being previously considered as highly important only at UPLs of above 1.1 V, our evidence suggests that it is in-fact the dominant mechanism responsible for the observed performance losses already at operating voltages relevant for operation of Pt-alloys in PEMFCs. Since transient dissolution of the less noble metal is highly connected with the transient dissolution of Pt, following this logic, perhaps operational strategies on the system level as well as modifications inhibiting Pt dissolution and improving the protection of the less noble metal should be of a much larger focus in the future (by for example addition of Au ). Thus, in our opinion, there are still large opportunities not only at investigation of novel chemical activation protocols, but also at the development of highly-stable high metal loaded/high ECSA Pt-alloy electrocatalysts. and also in how system-level operation of Pt-alloy electrocatalysts should be viewed in contrast to traditional Pt/C for extending the long-term performance benefits of this still intriguing class of PEMFC electrocatalysts.