Knowledge of materials is of paramount importance for effective nuclear reactor design and applications. With governments advocating new nuclear reactors in most parts of the world and the push towards the development of the Generation-IV reactors in select countries, a huge pool of well-trained nuclear engineers is required now and in the years to come. At the same time, the growth of this industry has been phenomenal all over the world. The present textbook covers both fundamental and advanced aspects of nuclear materials. It begins with an overview of nuclear reactor systems, which will help readers to get familiarized with varied designs. Then, the readers will be exposed to different possibilities of materials applications in different sections of nuclear energy systems - be it fuel rod assembly, steam generators, or piping. There will be a thorough coverage of various materials science principles, such as physical and mechanical metallurgy, defects and diffusion and radiation effects on materials. Throughout the whole book, serious efforts will be made to establish structure-property correlations wherever possible. Materials selection and life prediction methodologies for nuclear reactors will also be presented in relation to creep, corrosion and other degradation mechanisms. The final chapter will touch upon advanced topics of nuclear materials such as materials for space nuclear reactors, fusion reactors and other topics of interest. There will be an appendix compiling useful materials property data relevant for nuclear reactor applications. Each chapter will be followed by a summary, recommended references and problems. Relevant Course Codes: E5X550 - Power Engineering E71800 - Nuclear Engineering