Given the depletion of fossil fuels and global warming issues there is an intensified interest in microbial production of biofuels and -chemicals from renewable resources. First generation biofuel and -chemical production, using food crops as a feedstock, has resulted in the successful establishment of industrial processes such as bio-ethanol production. These processes are restricted to using a very limited set of well-established bacterial or eukaryal production platform organisms. However, because of the competition with human food consumption in first-generation processes there is a strong need for the transition towards second-generation microbial production processes in which lignocellulosic biomass (e.g. wood, grass) is used as a feedstock. This brings about challenges that can be overcome by using new extremophilic industrial hosts. In my project, I will engineer a butyric acid production pathway in the hyperthermoacidophilic archaeon Sulfolobus acidocaldarius. Butyric acid and the longer chain fatty acids have several applications (e.g. anti-sceptic, flavouring, cosmetics) and are important platform molecules for biofuels and -chemicals. Furthermore, I will develop an acyl-CoA responsive thermophilic biosensor and an achaeal promoter library. My project will contribute to the development of new thermophilic industrial hosts that enable the cost-efficient production of biofuels and -chemicals facilitating a shift towards a sustainable bio-based economy.