In this work we present a molecular level study of non-equilibrium dissociation and vibrational excitation of oxygen due to O2+ O2and O2+ O interactions using the direct molecular simulation method (DMS). The O2+O2interactions were modeled using potential energy surfaces (PESs) corresponding to the singlet and quintet spin states and isothermal excitation calculations were carried out over temperatures ranging from 5000K to 20000K to calculate non-equilibrium dissociation rate coefficients and characteristic vibrational excitation times over. Non-equilibrium dissociation rate coefficients obtained from both PESs for the O2+O2interactions are in agreement. The characteristic vibrational excitation times calculate calculated showed that the molecules colliding over the quintet surface excite slightly faster than those colliding on the singlet surface. The O2+O interactions were modeled using the four body PESs and placing an atom at a large distance from the three interacting atoms. While, this particular arrangement does not correspond to a specific state for the three body system it gives us a qualitative idea of the properties associated with O2+ O interactions. Dissociation rate coefficients and characteristic vibrational excitation times were calculated for the O2+ O interactions. Although preliminary, it was found that the dissociation rate coefficients obtained using the two PESs were similar and the characteristic vibrational excitation times obtained from the singlet PES were higher than those obtained from the the quintet PES.