High Entropy Alloys are a promising new class of materials. Specifically, PtPdFeCoNi showed promising activites for ORR, making it a possible candidate for as a next-generation catalyst for PEMFCs. However, there is little known about the degradation of alloys, especially this HEA. Anomalous SAXS at the Pt K-edge and total scattering will be used to gain valuable insights in the dealloying process. From other operando measurments, we see a formation of an extra phase corresponding to a Pt-fcc. With ASAXS, we can confirm whether we have a core-shell nanoparticle forming and track its evolution over time. Total Scattering will allow us to track the dealloying on an atomic scale. These results will be essential to increase our understanding of alloys, especially HEAs