Complex impedance spectroscopy and analytical transmission electron microscopy are used in a complementary fashion to understand the local defect chemistry and electrical properties of grain boundaries and interfaces in metal-oxide ceramics. High spatial resolution chemical analysis, including energy dispersive x-ray spectroscopy and electron energy loss spectroscopy are performed to understand the structure and microchemistry of the individual components of the microstructure (i.e. grain interiors, grain boundaries and interfaces). By measuring the impedance response of the material as a function of temperature, we are able to isolate the contributions of each microstructural component to the net impedance response. These techniques have been utilized to study grain boundary segregation in TiO 2 and degradation mechanisms in BaTiO 3-based multilayer ceramic capacitors.