In summary, to show the critical importance of the catalyst activation we have prepared four de-alloyed (chemically activated) Pt-M (M = Cu or Ni) electrocatalysts and compared them with the Pt-Ni alloy catalyst from Johnson Matthey. Namely, both Pt-alloys were subjected to either a 'milder' acetic acid activation protocol or a 'harsher' sulfuric acid activation protocol. Both A-and S-activated analogues were then evaluated using TF-RDE, inline metal dissolution using EFC-ICP-MS methodology as well as tested in the 50 cm 2 singlecells at both the hot-wet (80 o C, 100% RH) as well as the hot-dry (80 o C, 30% RH) conditions.