The Biomass represents an alternative and a relevant solution for using less fossil energy while presenting the environment. Therefore, the performance of the rapeseed oil as a fuel has been investigated in a 100 kW pre-pilot plant and the results have been compared with those obtained with light and heavy petroleum fuel oils. In particular, carbonaceous particles and PAH formation along the three spray flame axes have been studied by optical (Laser Light Scattering) and gas-solid sampling techniques. Additional measurements of the local value of the extinction coefficient compared to the scattering information made it possible to distinguish between soot particles and cenospheres, The kinetics of formation and burnout of the particulate matter identified in terms of number concentration of soot particles and cenospheres, have been evaluated. Moreover the results have shown that the rapeseed oil flame is less polluting than fossil oil flames.