A high pressure thermogravimetric analyser (HPTGA) has been used to explore the effect of total pressure (100, 200 and 300 psig) on the combustion behaviour and kinetics of crude oils. In combustion with air, three different reaction regions were identified, known as low-temperature oxidation, fuel deposition and high temperature oxidation. The Coats and Redfern procedure was applied to determine the kinetic parameters of the crude oils studied.