After its development in the 1950s, lead zirkonate titanate (Pb(ZrxTi1-x)O3, shortly PZT) has become one of the most important ferroelectric materials. PZT is used in ultrasonic generators, loudspeakers, microphones, actuators for precision positioning, or also for direct fuel injection systems in combustion engines. Electroceramics such as PZT are often strained by high electric field, which causes fatigue and degradation. However, degradation mechanisms of PZT are not completely understood. To investigate the degradation of PZT under high field stress, actuator stacks with copper inner electrodes are used. The degradation process is performed at elevated temperatures (350-550 C) and high DC-voltage (100-200V). During degradation and the subsequent relaxation the sample is characterized by impedance spectroscopy and light microscopy. Using microelectrodes cathodic and anodic processes are measured separately and local conductivity changes can be investigated after cathodic and anodic polarization. For further investigation of field induced (cat)ion movement in addition to impedance spectroscopy on stack material PZT thin films are synthetized and analyzed. The thin films are polarized by DC-voltage, and then the changes of cation concentrations are analyzed by ToF-SIMS. Based on the results it can be concluded that lead vacancies are mobile at given temperatures under field, furthermore, polarization generates space charge layers at grain boundaries.