This article presents the chemical analysis of jet fuel (Jet A-1) heteroatomic components generated as a result of thermal stressing. Jet A-1 was thermally stressed by flow and static tests in a single tube heat exchanger in the autoxidation regime (150-300 degrees C). Jet A-1 samples were analyzed by electrospray ion mass spectrometry (ESI-MS), Fourier transform infrared (FTIR) and C-13 nuclear magnetic resonance (NMR) spectroscopy. Mass spectra of Jet A-1 recorded higher molecular weight components in the mass range 300-1000 Da. FTIR spectra revealed absorption bands for oxygen-containing species such as alcohol, phenol, and ether. Jet A-1 NMR spectra recorded heteroatomic alkoxy species. A lichen substance, gyrophoric acid was identified as Jet A-1 component. ESI-MS, FTIR and NMR spectra of unstressed jet fuel recorded peaks corresponding with gyrophoric acid. Natural products polyphenols and lichen derived compounds are excellent antioxidants, and their advantages as potential fuel additives are discussed. (C) 2019 Elsevier Ltd. All rights reserved.