A miniature electrolyser cell was developed to image AEMWE degradation during operation. The cell's electrochemical performance was successfully validated against a typical 5 cm 2 lab test fixture. Lab-based μ-CT imaging revealed a > 50% reduction in membrane thickness and conductivity, as well as observable catalyst detachment in a Fumasep® FAA-3-50-based CCM after 20 h of stability testing. Any decrease in Ecell because of the thinner membrane was counteracted by loss of conductivity and/or catalyst during the stability test. The ability to correlate in-situ μ-CT images with electrochemical measurements enabled thinning of the Fumasep® membrane to be observed and ionic conductivity to be calculated; a finding that could not have been predicted by the Ecell and HFR measurements alone. Synchrotron-based operando μ-CT enabled membrane thickness to be measured every 2 h over the course of a 20 h stability test. Membrane thinning was shown to be non-linear, with a comparable halving in thickness after 20 h, despite a measurable increase in both the Ecell,iR corr. and the HFR. By comparison with lab-based tests, synchrotron X-rays were shown to have minimal effects on Fumasep® membrane thinning but exacerbated ionic conductivity degradation. In contrast, a Selemion™ based CCM experienced minimal changes in thickness, and the HFR and membrane conductivity were substantially more stable (≈ 80% vs. ≈ 20% retention over 12 h) when the cell was exposed to synchrotron radiation. These results show the importance of aryl ether free AEMs and challenges of operando studies at synchrotron facilities for AEMWEs. Overall, our work highlights the need for techniques like μ-CT to complement electrochemical testing and aid in better understanding of electrolyser degradation. The miniature cell was shown to be a robust platform for deconvoluting complex behaviour within a real electrolyser CCM and should have relevance for investigating the impact of new materials, compositions and operating conditions on electrolyser durability.