The influence of sulfur compounds on a fuel's thermal stability has been assessed under ASTM D7739 conditions using a range of jet fuels taken from in-service with known sulfur contents as well as a two component fuel surrogate. It was found that elemental sulfur, benzene sulfonic acid and diphenyl disulfide have the largest impact on sediment formation rates and that cyclic sulfides promote oxidation in model fuel. No correlation between sulfur types and thermal deposit formation from a range of thermally stable jet fuels was observed in this study.