To evaluate the performance of the new catalyst in a single cell, catalyst coated membranes (CCMs) were prepared by a standard decal method. The synthesized TiO2@IrOx catalyst material was compared to the commercial IrO2/TiO2 (Umicore Elyst Ir75 0480) catalyst. All CCMs consisted of an anode with either the core-shell or the Umicore catalyst, a Nafion NR212 membrane and a Pt/C cathode. Details on the CCM fabrication can be found in the ESI. The structure of the TiO2@IrOx catalyst layers was further analyzed by TEM on a lamella prepared via a focused ion beam (FIB) and by nano X-ray computed tomography (nano-CT). A structural comparison of the catalyst layers with the core-shell TiO2@IrOx catalyst and the commercial IrO2/TiO2 catalyst is done by FIB scanning electron microscopy (SEM) and cross-sectional imaging. The electrical conductivity of catalyst layers prepared with those two different catalysts has been measured additionally. Details on the structural analysis of the layers can be found in the ESI.