Abstract The use of alternative fuels is an essential element in future aviation. There are currently different approaches with regard to fuel production processes and feedstock materials. This requires flexible handling of available fuel quantities. The production of fuel mixtures (blends) is inevitable for an effective usage of commercially available fuel components. Within the framework of the project DEMO-SPK approx. 600 t of a ternary mixture (multiblend) of alternative jet fuels was produced and used in a real airport infrastructure at the airport Leipzig/Halle. Production and application were accompanied by extensive R&D activities to show that on-spec, semi-synthetic multiblends can be produced from several different synthetic fuels. One important aspect is the emission of soot particles from aircraft engines. The Multiblend Jet A-1 has been analyzed in a flow reactor setup regarding the formation of soot precursor compounds in comparison to a reference Jet A-1. The experiment revealed a lower formation of relevant soot precursors which also corresponds to the higher hydrogen content of the Multiblend Jet A-1 compared to the reference fuel. The lower soot formation in a real aircraft engine has been proven during ground runs of an A300-600 aircraft with PW4158 engines. The Multiblend Jet A-1 showed lower particle number and particle mass emission than the reference fuel. The difference to the reference fuel decreased with increasing power settings. In summary, the emission of particle mass is reduced by ~ 29 % and the number of emitted particles is reduced by ~ 37 % if the ICAO landing-and-take-off cycle is used for evaluation.