With the improvements in technologies to produce 2,5-dimethyfuran (DMF) from biomass such as cellulose, the potential of this biofuel to completely or partially replace fossil fuels in order to reduce our dependence on them and to curb pollutant emissions has been explored in some recent studies. In this work, the effect of the addition of DMF (up to 15% by volume) to diesel on the sooting propensity and on the oxidative reactivity and nanostructures of soot particles is studied using a diffusion flame. With increasing amount of DMF in the DMF/diesel blends, soot emission was found to reduce, while the oxidation reactivity of soot particles increased. The activation energies of soot oxidation from blended fuels were significantly lower than that of diesel soot. The increase in soot reactivity is linked with the changes in physical and chemical properties of soot nanostructures. Several experimental techniques such as high resolution transmission electron microscopy, electron energy loss spectroscopy, thermo-gravimetric analysis, elemental analysis, Fourier transform infrared spectroscopy, and X-ray diffraction have been used to identify the changes in structures, functional groups such as oxygenates and aliphatics, pi and sigma bonding, O/C and H/C ratios, and crystallite parameters of soot particles. With increasing DMF concentration in diesel, the sizes of primary particles and the polycyclic aromatic hydrocarbons (PAHs) comprising soot decreased, while the aliphatic character (sp3 hybridization) and the amount of oxygenated functional groups in it increased. The observations from soot characterization are used to explain the high susceptibility of soot particles from blended fuels toward oxidation. (C) 2015 Elsevier Ltd. All rights reserved.