Quantitative three-dimensional (3D) analysis of solid oxide fuel cell (SOFC) electrode microstructure has been shown to be a key means for connecting materials processing and electrochemical performance.  In addition, 3D imaging is being used to help observe and understand degradation mechanisms, important for developing degradation models that can predict long-term cell stability. This paper will describe 3D electrode tomography measurements, of various electrodes including Ni-Y-stabilized Zirconia (Ni-YSZ), (La,Sr)MnO₃-YSZ, and (La,Sr)(Fe,Co)O₃ (LSCF), made using focused ion beam scanning electron microscopy and transmission x-ray microscopy. Results on electrode structural evolution, and how the microstructure impacts electrochemical performance, will be described.  For the Ni-YSZ case, measured particle coarsening during high-temperature ageing is correlated with decreases in three-phase boundary density and increases in polarization resistance and a model developed to predict long-term degradation.  For LSCF, depending on ageing time and temperature, either particle coarsening or SrO surface segregation can impact electrode performance degradation.