Several group of cobalt-based catalysts will be analyzed using X-ray absorption and emission spectroscopy. (i) The first group of materials comprises of single-atom catalysts, Co/N/C, before and after accelerated stress test protocols in order to complete the datasets acquired previously. (ii) The feasibility study will be performed on the second group, Co-based polyoxometalates (POMs), where the latter are in a liquid form with different POM concentration. (iii) The third group of the catalysts are core-shell CoFe particles supported on gold substrate will be studied in situ under heating in the presence of dry air.