Synthesis of FeC2O42H2O nano particles was carried out by thermal double decomposition of solutions of oxalic acid dihydrate (C2H2O4 2H2O) and FeSO4 7H2O employing CATA -2R microwave reactor. Structural elucidation was carried out by employing X-ray diffraction, particle size and shape were studied by transmission electron microscopy and nature of bonding was investigated by Optical absorption and near-infrared spectral studies. The powder resulting from this method is possesses distorted rhombic octahedral structure. The particle grain size is about 50 nm. Details of optical transitions are mentioned in terms of energy states.