The invention provides a fully synthetic aviation fuel or aviation fuel component having: a total naphthenic content of more than 30 mass %, a mass ratio of naphthenic to iso-paraffinic hydrocarbon species of more than 1 and less than 15, a density (at 15° C.) of greater than 0.775 g·cm-3, but less than 0.850 g·cm-3, an aromatic hydrocarbon content of greater than 8 mass %, but less than 20 mass %, a freezing point of less than −47° C., a lubricity BOCLE WSD value of less than 0.85 mm. The invention further provides for the preparation of a fully synthetic coal-derived aviation fuel or aviation fuel component by blending a LFTF and a tar derived blend component. The invention extends to a method of producing a coal-derived, fully synthetic aviation fuel or aviation fuel component from coal gasifier tar and an LTLF derived fraction.