Undoped stochiometric PZT samples, Pb(ZrxTi1-x)O3, with different Zr/Ti ratios in a composition range from x = 0.60 to x = 0.45 across the morphotropic phase boundary (MPB) were prepared by the conventional mixed-oxide route from PbO, ZrO2 and TiO2 powders. A fundamental study of the local domain structure and orientation was carried out. The observed domain configurations were compared to the one theoretically predicted by Sapriel [1], Fousek and Janovec [2]. The domain structure of the range of samples investigated is strongly composition dependent. Compositions belonging to the tetragonal (45/55) and rhombohedral (60/40) phase field, not close to the MPB, show the appearance of a bimodal domain configuration with alternating latitudes. Around the morphotropic phase boundary a decrease in bimodal distribution is observed, accompanied by an increase in domain width and nanodomain formation within the large microdomains. In-situ hot-stage TEM experiments revealed domain wall motions and the appearance of domains at nanoscale during recooling. ESEM examinations have been undertaken as a complementarymethod to confirm the TEM experiments. The electronmicroscopical results were compared to high-resolution synchrotron X-Ray powder diffraction data measured at different temperatures in transmission geometry. In order to directly visualize the theoretically described domain switching process [3], additional in-situ electric-field TEM experiments are in preparation. This work was funded by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 595 ’’Elektrische Ermudung von Funktionswerkstoffen’’.