The use of biofuels as automotive fuels is gradually increasing in order to meet the legislation targets for the use of renewable products in road fuels. Many types of bio-blending components are already used for this purpose throughout Europe with Fatty Acid Methyl Esters (FAMEs) being the most common. The objective of the present study was to evaluate the impact of Rapeseed Methyl Ester (RME) application on unregulated particulate emissions of modern diesel passenger vehicles, and specifically on exhaust particles' most important chemical constituents. Particle emissions were analyzed for their soluble organic fraction (SOF) and its constituents (fuel-derived SOF and lube oil-derived SOF), as well as for major inorganic ions (nitrate, sulfate, ammonium). Furthermore, the impact of RME on SOF's redox activity was investigated. A hydrocarbon-only diesel fuel (B0) and three blends of RME at 10%, 30% and 50% v/v were tested with three Euro 4 + compliant vehicles, one equipped with an oxidation catalyst and two others with different type of Diesel Particulate Filters (DPF), over the NEDC and Artemis Urban driving cycles. The use of higher biodiesel blends seem to result in increased SOF percentage to the total PM emitted. The same trend was also observed for fuel-derived SOF, while lube oil-derived SOF and major ion percentages to total PM were not significantly affected by the fuel change. Fuel-derived SOF was the major constituent comprising from 70% to 90% of the total SOF emitted. Additionally, in the non-DPF equipped vehicle the increase of biodiesel blend resulted in increased n-alkanes emissions (mu g/km) without, however, the differences being statistically significant. Although the non-DPF equipped vehicle exhibited slightly higher sulfate than nitrate emissions, in DPF equipped vehicles sulfate were not detected at all. Higher RME contents resulted in elevated DTT-redox activity per mass in all tested vehicles, while on the other hand, the DTT-redox activity per unit of distance driven was not affected by the fuel change. Both DPF equipped vehicles exhibited 2-3 times higher DTT-redox activity per mass of emitted SOF when compared to the non-DPF equipped vehicle, however they exhibited 3-6 times lower oxidation activity per km, regardless the fuel. This is an indication that a significant amount of potentially more toxic organic compounds are trapped and oxidized in the DPF resulting thus in potentially less toxic organic emissions compared to the non-DPF equipped vehicle. (C) 2014 Elsevier Ltd. All rights reserved.