The production of nuclear waste is undoubtedly a major downside to nuclear energy. In the UK, much of our intermediate and high level waste is currently stored in temporary facilities with the aim of burying it in deep underground facilities by 2040. In order to achieve this, the radionuclides require immobilising to prevent them from leaching into the environment. This can be achieved by incorporating the radionuclides into minerals, ceramics or glasses before encapsulation in disposal containers. In order for a material to be successful in this role it must be chemically durable, thermally stable and radiation resistant. The current plan for the disposal of high level waste is to combine it with molten borosilicate glass before encapsulation in stainless steel containers (vitrification). This is a far from perfect solution however as, amongst other faults, these glasses have been found to undergo amorphisation of the newly-formed crystalline phase which over time can lead to microcracking and swelling; thus reducing the integrity of the wasteform. This study is therefore focused on ceramic wasteforms as an alternative to vitrification, specifically the orthosilicate, ASi04, and pyrochlore, A2B207, structure types. This research will describe how low temperature hydrothermal synthesis (at temperatures of just 150-240 QC) offers significantly greater control over the product structure and morphology than traditional solid state methods. The wasteform materials produced were also found to exhibit outstanding thcll11al stability and excellent chemical durability.