 Under operation of the fuel cell they determined the change of the particle size of and oxidation state and shell formation of the platinum electrocatalyst.In contrast to the SOFC operation conditions, this was a PEM-FC study in liquid environment under ambient temperature.The same operando method is applied to battery research and yields information on the changes of the oxidation state of electrochemically active elements in a cathode such as Mn via XANES, information on coronation shell and bond length via EXAFS, and information on microstructure changes during battery operation via ASAXS.