Biodiesel derived from corn oil promise to be an alternative for the conventional diesel fuel due to their similarity in properties. In this present work, silicon dioxide (SiO2) nanoparticles are used as an additive to the corn oil methyl ester (COME) in the form of an emulsion. SiO2 nanoparticles are dispersed in the emulsions with different dosage levels of 50, 75 and 100 ppm. A single cylinder, four-stroke, direct injection CI engine is made to run on B20, and B20 dozed with SiO2 nanoparticles for different concentrations to study the effect of metal oxide nanoparticles on emission characteristics of the fuel. Experimental results show that addition of nanoparticles has a positive effect on emission characteristics as nanoparticles act as an oxidation catalyst.