Supporting metal nanoparticles is a common approach in heterogeneous gas-phase catalysis to decrease the metal loading, prevent agglomeration and thus minimize the cost of a catalytic conversion. This approach proved particularly successful in proton-exchange membrane fuel cells (PEMFC) where the replacement of Pt-blacks (used in early PEMFCs) by carbon-supported Pt nanoparticles has significantly improved the Pt specific power density. Using the same material’s concepts in proton-exchange membrane water electrolysers (PEMWE) could minimize the noble metal loading especially at the anode where the oxygen evolution reaction (OER) takes place. However, high-surface area carbon supports are rapidly degraded in the operating conditions of a PEMWE anode (E > 1.6 V vs. the reversible hydrogen electrode, T = 80 °C) calling for alternative support materials. In this contribution, Ir nanoparticles have been deposited on different types of antimony doped tin dioxide (ATO) and on Vulcan XC72 as a reference support. Identical-location transmission electron microscopy (IL-TEM) experiments revealed improved stability of Ir nanoparticles supported onto ATO under simulated operating conditions of a PEMWE anode, therefore opening new possibilities for the rational design of highly-active, cost-efficient and stable OER catalysts.