Summary:Extended Huckel molecular orbital calculations were performed on various peroxides (hydroperoxides, peracids, and peresters), nitrites, nitrates, esters, ethers, and alcohols with particular reference to the bond nature of their O-O, O-N, C-O, and O-H linkages. We made several findings. Firstly, the order of the bond strengths of the above linkages in the compounds considered was: alcohol>ester>ether>>nitrate>nitrite>>hydroperoxide>peroxide>perester> peracid. Secondly, peroxide families or nitrite and nitrate families were characterized by the lowest unoccupied (or the LU+1), antibonding O-O or O-N linkages. Thirdly, a parallel between the overlap population of the above linkages (O-O or O-N) and their bond dissociation energies could be recognized, with certain irregularities. Fourthly, the monomer structures of alkyl hydroperoxides were more energetically stable and reactive to nucleophiles than dimer ones. Finally, the characteristic bond nature of the above linkages was discussed in connection with the wave function contours.