ABSTRACT The use of diesel particulate filter (DPF) has become a standard after treatment technology in modern diesel engine however; pressure drop develops across the filter as PM accumulates. This requires quick periodic burn-out without incurring thermal runaway temperatures that could compromise DPF integrity in operation. Adequate understanding of soot oxidation is central to design and manufacture of efficient filter traps suitable for the engine system. In this study, we have examined the oxidation of PM generated from a high speed direct injection (HSDI) diesel engine, ran with 20% and 40% blends of two biodiesel fuels. The PM samples were collected on a Pall Tissuquartz filter during constant engine load and oxidised non-isothermally in a thermogravimetric analyser (TGA). Then results obtained are compared with PM oxidation data obtained from pure petrodiesel. There is significant demonstration of the influence of biodiesel blending on PM emission and oxidation characteristics. This is viewed to be largely due to biodiesel oxygen content and microstructure of soot arising from it. Keywords: Particulate Matter (PM), Oxidation, Biodiesel, Petrodiesel, Blending.