The authors present the results of own research on the application of biofuels and depolymers and their mixtures with diesel fuel and the influence of this type of fueling on the exhaust emissions against standard fuel. The authors have observed that the application of bio-depolymer fuel (BIO+DEP)/20 does not deteriorate the engine operating parameters particularly in medium engine loads and speeds. The reduction of the PM emission generated by the diesel engines caused by the investigated bio-components and fuel depolymers occurs due to a reduction of the share of the INSOL fraction in the total mass of the emitted PM. The change in the combustion process when fueled with (BIO+DEP)/20 (caused by the compensative influence of the viscosity, density and an increase in CN in particular) also results in a reduction of the exhaust emissions of the outstanding exhaust components.