22Cell-free synthetic biochemistry provides a green solution to replace traditional 23 petroleum or agricultural based methods for production of fine chemicals. 4-(4-24 hydroxyphenyl)-butan-2-one, also known as raspberry ketone, is the major fragrance 25 component of raspberry fruit and is utilised as a natural additive in the food and 26 sports industry. Current industrial processing standards involve chemical extraction 27with a yield of 1-4 mg per kilo of fruit. As such its market price can fluctuate up to 28 $20,000 per kg. Metabolic engineering approaches to synthesise this molecule by 29 microbial fermentation have only resulted in low yields of up to 5 mg L -1 . In contrast, 30 cell-free synthetic biochemistry offers an intriguing compromise to the engineering 31 constraints provided by the living cell. Using purified enzymes or a two-step semi-32 synthetic route, an optimised pathway was formed for raspberry ketone synthesis 33 leading up to 100% yield conversion. The semi-synthetic route is potentially scalable 34 and cost-efficient for industrial synthesis of raspberry ketone.