Operando μ-CT of an AEMWE was performed in the ME-cell using synchrotron radiation to image changes in the CCM during 16 h of operation at a current density of 1 A cm -2 . To correlate the changes observed in the CCM with Ecell and HFR, μ-CT was performed every 2 h during a 15-min OCP break. EIS measurements were made before and after each OCP break. Example μ-CT slices from the operando study on with Fumasep® FAA-3-50 showing a cross-section of the cell in the pristine and degraded state are provided in Figure in the SI.