The structural and bonding properties of the chlorine oxides and peroxides ClOx, ClOx- (x = 1-4) and Cl2Ox (x = 1-8) in their ground state have been investigated with the hybrid spin unrestricted and spin :restricted Hartree-Fock density functional method. The equilibrium Structures of the most stable isomers in each stoichiometry have been determined. It is found that the di-chlorine,oxides avoid the formation of a Cl-Cl bond, and therefore have either an oxo or peroxo structure-The calculated vibrational harmonic frequencies are in good agreement with the available gas phase or matrix isolation IR data. The calculated adiabatic electron affinities of the mono-chlorine species are, respectively, 2.23, 2.14, 4.07, and 5.1 eV for ClO, ClO2, ClO3, and ClO4. The reaction enthalpies of the possible channels leading to the formation of di-chlorine oxides and peroxides Cl2Ox, from mono-chlorine oxide fragments are reported and discussed. A comparative discussion of the bonding in these species has been carried out on the basis-of the topological analysis of the electron localization function (ELF). It is found that the odd electron of the mono-chlorine species is distributed on the oxygen and chlorine lone pairs. The weak populations of the ClO bond basins and the absence of spin density within them leads to discarding a picture in:which three electrons are involved in the ClO bond. The localization of the spin density in the mono-chlorine oxides determines the reactive center: oxygen for ClO and ClO4, chlorine for ClO2 and ClO3. The formation of the di-chlorine oxides and peroxides from the mono-chlorinated species follows the two following rules: (i) the formation of a Cl-Cl bond never yields the most stable isomer, (ii) the chemical bond linking the two fragments is formed between their reactive centers provided rule (i) is satisfied.