Diesel particulate matter (DPM) is inevitably a by-product of incomplete combustion in diesel engines. It is composed primarily of unburned hydrocarbons, known as soluble organic fraction (SOF), and elemental carbon (or diesel soot). Characterization of the DPM has been the subject of comprehensive analysis by researchers from different disciplines due to its adverse health and environmental impacts. Many efforts are being made to reduce the amount of soot emitted or enhance its oxidation characteristics. One of these methods is to use oxygenated fuels. Methyl Tert-Butyl Ether (MTBE) was added to diesel fuel to study its effect on soot oxidative reactivity. A four-stroke single cylinder commercial diesel engine was used to generate raw exhaust soot. Nonisothermal oxidation kinetics of the soot samples were studied by the thrmogravimetric analyzer (TGA). Results showed that diesel and MTBE soot samples have similar activation energy but the pre-exponential factor of MTBE soot is much higher than the diesel soot. Therefore, MTBE soot has higher reactivity than diesel soot. X-ray diffraction (XRD) experiments resulted in similar crystallite dimensions for both types of soot. The elemental analysis showed that MTBE soot has higher atomic H/C ratio than the diesel soot, which, partly explains the higher reactivity of MTBE soot.