The first jet fuels were aviation gasoline (avgas), and the characteristics of subsequent jet fuels have evolved from this original choice, the available supply infrastructure, and the refiners' capabilities. Earlier on, it was evident that avgas would have to be altered to operate satisfactorily in jet powered aircraft. The present contribution outlines the various requirements that led to development of various operational jet fuels, including United States Jet A (European Jet A-1), JP-4 (NATO code, F-40), JP-5 (NATO code, F-44), JP-7 (US only), JP-8 (F-34), JP-TS (US only), and JP-8 + 100. To reduce this fuel logistic burden, the NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate Diesel fuel in many applications. In order to make this type of fuel compatible with direct injection compression engines, the Fuels and Lubricants Laboratory of the National Technical University of Athens, used a stationary Diesel engine fueled with fuel blends containing two different types of biodiesel, at proportions up to 50%. In this paper, fuel consumption and exhaust emission measurements from a single cylinder, stationary, Diesel engine are described. The two types of biodiesel appeared to have equal performance, and irrespective of the raw material used for their production, their addition to the JP-8 aviation fuel improved the particulate matter emissions.