Natural fibres offer a route to the production of sustainable composites, replacing inorganic and petrochemical based fibres with high-embodied energy. One of the main obstacles to the exploitation of natural fibres is the limited consistency of supply, with batch-to-batch variations in quality. Retting – a process whereby plant stems are left to weather in the fields – has been identified as being the weak point in fibre processing in the as a result of variable weather conditions during the retting period. Mechanical decortication – the removal of the outer layers – is often damaging to the fibres. UltraFibre will develop a clean processing technology called ‘hydroacoutstic decorticaton’ to extract the fibre from the plant after harvesting avoiding reliance on degree of dew retting. The fibre produced will be of much higher quality, without the physical damage caused by mechanical decortication, circumventing reliance on unpredictable weather for completion of dew retting in fields. Chemical treatments have been used to modify fibres to improve matrix to fibre adhesion in composite materials. However, these chemical treatments use hazardous materials, are time-consuming and create a significant level of waste. Therefore, a treatment process that does not pose a threat to the natural environment and that is reproducible, whilst creating little or no hazardous waste, would be extremely advantageous. To achieve this end, UltraFibre will develop a ‘soft plasma’ treatment process that will integrate with the hydroacoustic decortication process to produce high quality fibre for the rapidly expanding composites materials sector.