Future nuclear power systems, both fission and fusion, rely on the development of materials which can withstand some of the most extreme engineering environments. These include temperatures up to 1500oC, high fluxes of high energy neutrons and effects of gaseous elements produced by transmutation and implantation from the plasmas. Due to efforts to minimise the production of nuclear waste by such reactors the elements which may be used in structural components is limited and in many cases there is a lack of understanding of the basic deformation processes occur in ether pure materials or alloys and importantly how these are affected by temperature, radiation damage and gas content. This project will build upon the expertise in the MFFP and Micromechanics groups on high temperature mechanical testing at the micro and nano-scale. Facilities include two high temperature nanoindenters (-50oC to 950oC), including in-situ capabilities alongside dedicated FIB-SEM and FEG-SEM with EBSD. In addition we have access to state of the art computer codes for strain gradient crystal plasticity finite element modelling and discrete dislocation plasticity modelling. Both nanoindentation, micro-compression and micro-bend experiments will be used to study plastic deformation, fracture and creep in a range of novel high temperature materials (likely Fe, SiC or Zr based) with potential for use in future fusion reactors. HR-EBSD and AFM will be used to study deformation structures produced during testing and to inform strain gradient crystal plasticity finite element and discrete dislocation models. This will allow for a fuller understanding of the underlying physics of deformation in these materials both before and after irradiation or gas implantation. Strong links will be made to activities within the Culham Centre for Fusion Energy.