Corrosiveness of palm oil biodiesel blends was measured using surface plasmon resonance with polypyrrole chitosan cobalt ferrite nanoparticles sensing layers. Diesel fuel which is relatively corrosive and lower flash point is often mixed with biodiesel of low corrosiveness and higher flash point. Biodiesel blend fuels were prepared from the mixture of normal palm oil biodiesel and diesel fuel where the percentage of the mixture was in the range of 10–90%. The corrosiveness of all the samples was in the class 1a according to the standard copper strip test, but the concentrations of copper and iron ion that were released in biodiesel blend were distinctly different. In this article, the corrosiveness of biodiesel blend was investigated using surface plasmon resonance from the measurement the concentration of copper and iron ions. The corrosiveness of biodiesel blends consistently decreased with increasing the concentration of biodiesel. Moreover, the sensitivity of polypyrrole chitosan /cobalt ferrite and polypyrrole chitosan sensing layer was compared. Consequently, the polypyrrole chitosan cobalt ferrites have sensitivity higher than polypyrrole chitosan sensing layer.