The main objectives of WP5 are the thermochemical/catalytic upgrading of lignin and its pyrolysis bio-oil, hemicellulose and lipids streams towards aviation and/or bunker type fuels. More specifically, AUTH research focuses on the catalytic hydrodeoxygenation of the light fraction of lignin pyrolysis bio-oil towards (alkyl)cyclohexanes which can be utilized as drop-in aviation biofuels. Furthermore, mild hydrotreatment of the heavy fraction of lignin bio-oil can provide a partially deoxygenated stream which can be used as bunker fuels. On the other hand, deep hydrodeoxygenation under more intense conditions can lead to aviation biofuels. Towards to this aim, novel bifunctional and non-sulfided catalysts are developed and their properties (porosity and acidity) are tuned to increase the hydrodeoxygenation efficiency. Current results showed the complete hydrodeoxygenation of the light fraction and its highly potential to be considered in aviation biofuel mix. Moreover, further work is needed to complete deoxygenation of the heavier fraction, which however, may exhibit potential interest as bunker fuel component. Another objective for AUTH within the Flexi-Green Fuels project is the valorisation of the hemicellulose stream, coming from the organosolv biomass pretreatment, towards aviation fuels via cascade thermocatalytic processes. Xylose-rich streams are hydrolysed/dehydrated to furfural which is converted to furanic condensates via aldol condensation. Downstream hydrogenation/deoxygenation processes are applied to obtain C₈-C₁₇ linear alkanes which can be utilized as aviation fuels. Part of this research has been presented in various national and international conferences and is under submission to peer reviewed journals.