This research project aims to improve ferroelectric materials using nanostructures and complex layered-structured compounds. The interested ferroelectric materials include Pb-base compounds, i.e. lead zirconate titanate (PZT) and lead magnesium niobate titanate (PMNT), and lead free compounds, i.e. strontium bismuth niobate (SBN) and strontium bismuth tantalate (SBT). Several new ferroelectric systems were fabricated in this project. Some systems were in a form of thin film, while most of them were in a ceramic form. Therefore, fabrication process for high quality materials, microstructure, chemical composition and electrical properties were carefully studied in details. In this final research project will present 3 research parts that were completely done which are shown below. The first part of this research studied microstructure and electrical properties of PZTbased nanocomposite thin films which were synthesized by a triol sol-gel process and a spincoating. PZT/xWO3 and PZT/xCuO nanocomposite thin films (when x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1.0 wt%) were prepared. The dielectric and ferroelectric properties results showed decreasing trends with an increase in WO3 and CuO additional contents. However, the maximum dielectric values were observed for PZT/1wt%WO3 and PZT/0.2wt%CuO. Fatigue behaviour of PZT films were improved by an addition of nanoparticles. PZT/WO3 thin films exhibited a soft PZT characteristic while PZT/CuO films exhibited a hard PZT characteristic. The soft PZT thin films showed a significant improvement in polarization fatigue compared to those of pure PZT and hard PZT thin films. The second part of this research studied the effects of oxide nano-particle addition on electrical properties of PMNT ceramic. PMNT/xZnO (when x = 0, 0.4, 2.0, 4.0 and 11.0 mol%) and PMNT/yCuO (when y = 0, 0.2, 0.4, 2.0 and 4.0 mol%) were fabricated. The results of dielectric properties showed that an addition of ZnO at x ≤ 4.0 mol% caused a decrease in a maximum dielectric constant. But this value was significantly increased again at x ≤ 11.0 mol%. The ferroelectric analytical results of the ceramics showed that the remanent polarization and coercive field tended to increase with an increase in added-ZnO content. The induced strain and electrostrictive coefficient reached the maximum values at the composition of 2.0 mol% of ZnO. The results of dielectric properties of PMNT/CuO showed that with CuO content ≤ 0.4 mol%, the maximum dielectric constant tended to decrease. However, the maximum dielectric constant increased again with at y = 2.0 mol%. The ferroelectric results showed that the remanent polarization and coercive field tended to increase with an increase in CuO content. With y ≤ 2.0 mol%, the induced strain and electrostrictive coefficient of the ceramics tended to increase with an increase in y. The third part of this research studied the fabrication and characterization of ferroelectric PZT added with complex layer-structured perovskite compounds of SBT and SBN. This research prepared (1-x)PZT-xSBN and (1-x)PZT-xSBT (when x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0 weight fraction). The maximum value of dielectric constant was found in 0.9PZT- 0.1SBN and 0.9PZT-0.1SBT ceramics. The values were decreased with further increase in the amount of SBN or SBT. Ferroelectric property measurements showed that an addition of a small amount of SBN or SBT (x = 0.1) into PZT improved coercive field, remanent polarization and loop squareness. Further increasing the amount of SBN or SBT degraded the ferroelectric properties. For piezoelectric properties, the addition of small amounts of SBN or SBT with x = 0.1 could improve the piezoelectric coefficient of PZT ceramic. To conclude, this research was successful in fabrication, study of relations between fabrication, structure and properties of new ferroelectric systems. The results provided insight understanding of property changes upon processing condition and amount of additional phases. This research suggested further research direction and development of these materials for actual applications in electronic industries. The most important outputs of this research were 16 international publications, 5 national publications and 59 presentations in the international and national conferences. Throughout 3 year research, this project has truly created both nationally and internationally corroborations. This project played an important part in production of 1 BSc, 2 MSc and 6 PhD students. Most of these students were granted by different National scholarships such as the Royal Golden Jubilee PhD program (RGJ) under the Thailand Research Fund, and the Office of the Higher Education Commission (OHEC) under the program Strategic Scholarships for Frontier Research Network for the Ph.D. Program Doctoral degree.