The electrochemical performances of the synthesized TiO2@IrOx catalyst, the synthesized catalyst without shell (denoted as IrOx/TiO2) and the two commercial references IrOx (Alfa Aesar Premion) and IrO2/TiO2 (Umicore Elyst Ir75 0480) were characterized in rotating disc electrode (RDE) measurements. Additionally, the iridium dissolution during electrochemical testing was measured with a scanning flow cell (SFC) coupled on-line to an inductively coupled plasma mass spectrometer (ICP-MS). Both measurement techniques were performed in Argon-purged 0.1 M HClO4 at room temperature and a loading of 50 µgIr cm -2 and 10 µgIr cm -2 for RDE and SFC-ICP-MS measurements, respectively. The experimental details of both techniques are given in the ESI.