The autoxidation of jet fuel takeup place via a complex free reaction that involves the decomposition of hydroperoxides. The liquid-phase, unimolecular decomposition of hydroperoxide has been isolated for experimental study. Three hydroperoxides relevant to jet fuel autoxidation, including cumene hydroperoxide (CHP), dodecane hydroperoxide (DHP), and ethylbenzene hydroperoxide (EBHP), were thermally, decomposed separately and found to closely fit first-order behavior with respect to hydroperoxide concentration. The activation energy for liquid phase thermolysis of these hydroperoxides was found to be significantly less than typical gas-phase values. Parameters affecting the rate of hydroperoxide decomposition, such as dissolved metal content, organic adds, and metal deactivator additive (MDA) were explore. Metal type was shown to be a significant factor affecting hydroperoxide decomposition rate, while naphthenic acids (NA) re to have little effect on the rate. However, when dissolved metal and NA were added together a strong synergistic effect on hydroperoxide decomposition rate was noted. The increases in decomposition rate due to dissolved metal and/or acid were effectively inhibited by treatment with MDA.