Meeting increasing energy demands, storage demands and energy portability in a clean efficient manner will be expedited through an ability to directly image and analyse solid oxide fuel cell (SOFC) materials and components. In particular, the performance of SOFC electrodes is dependent on their nano/micro-structure as electrochemical reactions and transport phenomena are strongly affected by their complex porous microstructure. Furthermore, during processing or operation, microstructural evolution may degrade electrochemical performance. Tomographic techniques allow the 3D imaging and characterisation of complex microstructures at length scales down towards tens of nanometers; which are inadequately described in 2D. While performance is acknowledged to be dependent on reactions at electrode surfaces and interfaces, the detailed nature of these in technological electrodes is still not fully understood. Here we use tomographic techniques to probe the 3D SOFC electrode structure at nanometer to micrometer length scales. For the first time characterisation of specific necks and interfaces within SOFC electrodes is derived. Micro/nano structural changes are followed to facilitate understanding the differences which occur with shape, structures and morphology at high resolution. These are correlated with measured experimental values to provide insight into microstructure-property relationships. In doing so, the engineering of tailored electrodes during 3D printing is afforded. When coupled with electrochemical and thermo-mechanical computational models, the results show that nano/microstructural and compositional variations can significantly affect performance of SOFC electrodes. This coupled approach provides important insights for electrode design and understanding the sources of performance degradation. Figure 1