Under this study all electrocatalyst powders were treated under identical conditions during ink formulation (I/C ratio of 0.9) and all catalyst layers were printed and treated identically. As a result, it was observed, that the Pt cathode loading on A-activated analogues were higher than S-activated analogues. This is most likely due to different presences of transition metal cations in the catalyst inks that affected the ink viscosity. However, the mass activity results reported correct for the difference in Pt loading. First and foremost, it is interesting that despite d-Pt-Cu/C-NIC-A being the most active electrocatalyst according to TF-RDE characterization (Table ), it has the lowest MA among all the investigated electrocatalysts. This already suggests that presence of Cu ions in a single cell is significantly more damaging than Ni (similarly as Co ). On the other hand, the kinetic performance of d-Pt-Ni/C-NIC-A is also worse than that of the S-activated catalyst despite the trend being reversed in TF-RDE (Table ). In addition, there is also a slight increase in ECSACO as a result of dissolved pure Ni phase upon exposure of the electrocatalyst to the S-activation protocol (Figure ). This trend is in good agreement with the ECSA evaluation by TF-RDE (Table ). In contrast to A-activated catalysts, results of both S-activated Pt-alloys catalysts provide a similar kinetic performance at low current densities against the d-Pt-Ni/C-JM benchmark. Furthermore, with exception of d-Pt-Cu/C-NIC-A, the trends are in good agreement with the TF-RDE data (Table ), where kinetic performances of S-activated electrocatalysts were also comparable to that of the d-Pt-Ni/C-JM benchmark.