Ferroelectric thin film have recieved much attention in recent years because of their useful ferroelectric and dielectric properties to the device industry. In this article, we will address the relationship between the microstructure and the corresponding dielectric properties of PT and PZT ferroelectric thin film grown by Metal-Organic Chemical Vapor Deposition (MOCVD). The formation of domains in the textured polycrystalline thin films and single crystalline thin films were studied using TEM micrographs, X-ray diffraction and AFM. Substrate materials included single crystalline MgO, LaAlO3 and highly textured LaNiO3 coated Si substrate. The domain stability is also addressed as a result of initial cooling after deposition, and of subsequent thermal cycling after initial cooling. The stability of electrical properties after repeated cycles of operation (i. e. fatigue behavior) are also discussed.