In addition to the possible introduction of transition metal cations in the MEA during the phases of electrocatalyst ink preparation and/or CCM fabrication, the leaching can also occur during the break-in procedures and/or because of the Pt-M electrocatalysts degradation that results in metal dissolution . However, on the topic of metal dissolution, not only the intrinsic properties of an electrocatalyst material, but also the operational conditions of the PEMFC seem to play a crucial role. There is important evidence in the literature that highlight the significance of both the upper voltage limit (UVL), as well as the lower voltage limit (LVL) at limiting the degradation of Pt-based carbon supported electrocatalysts in the PEMFC. For instance, Uchimura and co-workers showed that ECSA loss increases when LVL is reduced from 0.8 V to 0.6 V when performing accelerated degradation test cycles while using a fixed UVL (0.95 V). At that time, the transient nature of Pt dissolution has not been fully understood and thus, the mechanistic interpretation of the increased degradation has not yet considered significant Pt dissolution arising from the de-stabilisation of the Pt-oxide species. This has been changed with the introduction of coupling methodologies between electrochemical cells and an inductively coupled plasma mass spectrometer (ICP-MS) that enabled time-and-potential resolved monitoring of dissolution of metals. The investigations revealed a significant link between Pt-dissolution and cathodically reduced Pt-oxide resulting from the so-called oxideplace exchange mechanism. Lastly, Yoshida and co-workers affirmed already during the launch of the 1 st generation Toyota Mirai the importance of limiting both the UVL and LVL to increase the fuel cell lifetime. This has been later confirmed during the investigation of the 1 st generation Toyota Mirai stack as part of the Department of Energy (DoE) Mirai Fuel Cell Vehicle report, revealing system-level limitations on the LVL of the stack . While high UVLs occurring during the start-up/shut-down of the PEMFC lead to severe carbon corrosion , the LVL seems to also play a significant role that is perhaps in particular importance for the successful implementation of Pt-alloys. For this reason further fundamental insights are necessary to truly understand this phenomenon. Thus, in the present work, particular attention was given to the effect of the de-alloying (activation) step on the performance with TF-RDEs and in 50 cm 2 MEAs in single-cells under a range of conditions. Furthermore, an additional link is established that connects the dealloying step with the observed TF-RDE features, in-line metal dissolution trends (using electrochemical flow cell (EFC) coupled to an inductively coupled plasma mass spectrometer (ICP-MS)) and corresponding single-cell performances. In addition, the effect of the LVL on the stability of Pt-alloys towards the dissolution of the less noble metal was investigated by a combination of both in-line metal dissolution measurements and accelerated degradation tests (ADT) in 50 cm 2 single-cell data.