flexJET is a four-year project part funded by the European Commission through the Horizon 2020 research initiative. The innovative flexJET project is diversifying the feedstock for sustainable aviation fuel (SAF) beyond vegetable oils and fats to biocrude oil produced from a wide range of organic waste. This is also one of the first technologies to use green hydrogen from the processed waste feedstock for the downstream refining process thereby maximising greenhouse gas savings and further contributing towards the Paris Agreement GHG reduction goals. The flexJET process is highly scalable and less capital-intensive than current technologies and can be integrated into existing infrastructure. It provides for a sustainable, cost-competitive aviation fuel by combining regional and local supply and demand strategies in a circular economy. As a key factor to the decarbonisation of the aviation transport sector, it contributes to the Renewable Energy Directive Targets in Europe and to the fulfilment of the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) goals. The consortium with 13 partner organisations has brought together some of the leading researchers, industrial technology providers and renewable energy experts from across Europe, in a collaborative, committed and dedicated research effort to deliver the overarching ambition.