Abstract: The global adiabatic and quasidiabatic potential energy surfaces for the ground and first three excited (1-43A″) electronic states of H ++ O 2 system are reported on a finer grid points in the Jacobi coordinates using Dunning’s cc-pVTZ basis set and internally contracted multi-reference (single and double) configuration interaction method. Ab initio procedures have been used to compute the corresponding quasidiabatic surfaces and radial coupling potentials which are relevant for the dynamical studies of inelastic vibrational excitation and charge transfer processes. Nonadiabatic couplings arising out of relative motion of proton and the vibrational motions of O 2 between the adiabatic electronic states have also been analyzed. Graphical abstract: Adiabatic and quasidiabatic potential energy surfaces have been constructed using ab initio procedure for the lowest four 1-4 3A′ ′ electronic states of H + + O 2 collision system. The computed quasidiabatic surfaces and coupling potentials would be helpful in understanding the collision dynamics of inelastic and charge transfer processes in the system. [Figure not available: see fulltext.]. © 2018, Indian Academy of Sciences.