Molecular orbital energies for about 30 nitroaromatic and nitroheterocyclic compounds have been calculated by CNDO/2 method, Calculated results of benzene, imidazole, furan and their nitro compounds have demonstrated that the lowest empty orbital energies of nitro substituted compounds are lower than that of their parent compounds, e. g, electron affinities of these nitro compounds are higher than that of the parent compounds. The positive charge is concentrated on nitrogen atom of these nitro compounds. Thus, in these electrophilic nitro compounds, the presence of nitro group is important for forming their electron-adduct.,We have calculated 11 substituted nitroimidazoles, 13 substituted nitrobenzenes and 7 substituted nitrofurans. Good linear relationships have been found between the calculated energies of the lowest empty molecular orbits(E,LEMO, eV)and one-electron reduction potentials(,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648114&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648116&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648115&type=,) measured by pulse radiolysis technique. In the case of the substituted nitroimidazoles, a good linear relationship has been obtained between the calculated lowest empty orbital energies(E,LEMO, eV) and concentrations of sensitizers C,1.6,. The calculated results have indicated that the electrophilic sensitizer is a substance with higher EA and IP than that of target molecule, that is to say, both its lowest empty orbital energies and highest occupied orbital energies are lower than that of the target molecule.