An ab initio study on the low-lying potential energy surfaces of H + + O2 system for different orientations (γ) of H+ have been undertaken employing the multi-reference configuration interaction (MRCI) method and Dunning's cc-pVTZ basis set to examine their role in influencing the collision dynamics. Nonadiabatic interactions have been analysed for the 2 × 2 case in two dimensions for γ= 0°, 45° and 90°, and the corresponding diabatic potential energy surfaces have been obtained using the diabatic wavefunctions and their CI coefficients. The characteristics of the collision dynamics have been analysed in terms of vibrational coupling matrix elements for both inelastic and charge transfer processes in the restricted geometries. The strengths of coupling matrix elements reflect the vibrational excitation patterns observed in the state-to-state beam experiments. © Indian Academy of Sciences.