Important Generation IV criteria for advanced fuel cycles are both improved efficiency and economical competitiveness. To reach these goals and keep high safety standards a key item is the availability of suitable structural materials. Ferritic/Martensitic (F/M) and Oxide-Dispersion-Strengthened (ODS) steels are indicated as the most promising candidates to withstand temperature, stress and irradiation fields expected in the core and primary system of most of the new generation reactors. In this context, the “Generation IV and Transmutation Materials” (GETMAT) project, sponsored by the EC, will contribute to the characterisation of ODS and F/M steels. The experimental and phenomenological aspects are complemented by the development of physical models aimed at describing and possibly predicting materials performance in operation.