Jet fuel stability is an important fuel property for management of fuel in storage. A method for predicting jet fuel stability, based on the colourimetric reaction of the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) has been examined in this work. A range of jet fuels of known and unknown refining history, including a range of antioxidant compounds have been examined using the DPPH assay with mixed results. It was found that the DPPH technique responds predictably with a range of phenolic species however was less predictable with jet fuels of unknown provenance. Little to no correlation was observed when comparing unknown fuels storage stabilities based on oxidative and peroxide formation tests against the DPPH assay, however a good correlation was observed for fuels of known refining history for these same storage stability tests. The wide variation of results may in part be due to the very complex reaction mechanisms of DPPH with species in the fuels and due to the inherent chemical complexity of middle distillate fuels that may have undergone ageing reactions in storage prior testing with the DPPH assay. (C) 2017 Elsevier Ltd. All rights reserved.