At this investigation, soot oxidation kinetics diesel PM and palm biodiesel PM from a single cylinder engine at 80% load is investigated by conventional TGA analyze in the isothermal condition. Nitrogen is used as the inert gas and then air is introduced for soot oxidation. Mass conversion, order of carbon in reaction and apparent activation energy of all samples were analyzed at different fractions of conversion for each sample. The soot sample from biodiesel shows better oxidation behavior.