Coffee’s global appeal is related to its unique flavour, taste and mouthfeel. Coffee is the second-most traded global commodity after petroleum, and a thorough understanding of the chemical dynamics associated with its aroma is essential for the enhancement and permanence of its popularity. This chapter covers the chemical composition of green coffee beans, the process of roasting, the profile of volatile and non-volatile compounds generated by roasting and the chemical reactions responsible for their formation. We use research from the 1990s to the present to discuss the presence of incidental compounds in roasted coffee, the influence of coffee processing on aroma profile and the central issue of key volatiles in the determination of coffee aroma. Finally, we provide insights regarding future directions in the elucidation of coffee flavour.