Cobalt oxide (Co3O4) polyhedron are synthesized by using microwave assisted wet chemical synthesis approach. The structural model of Co3O4 has been predicted on the basis of X-ray diffraction analysis. It is observed that positions of all cobalt ions are not same. The structural parameters of unit cell are calculated. The calculated values of various structural parameters have compared with that of standard values here. The morphology of product has been analyzed with help of scanning and transmission electron microscopies. The lengths of all dimensions of polyhedron are measured from TEM images. The catalytic activity of Co3O4 nanoparticles are tested against dry and aqueous media reactions. Moreover the role of nanoparticles as an additive in kerosene as fuel is also studied. The properties of fuel in the absence of nanoparticles are found to be different from that of presence of nanoparticles.