Global ab initio potential energy surfaces for the ground (1 (2)A(1)) and the first excited (1 B-2(2)) electronic states of NO2 are presented. The calculations are performed at a multireference configuration interaction level with the correlation consistent quadruple zeta atomic basis set of Dunning (cc-pVQZ). A total of about 5000 ab initio points were calculated. The dissociation energy corresponding to NO2-->NO+O and other features of the surfaces are found to be in close agreement with experimental values. The adiabatic ground and the first excited electronic states form a conical intersection and have been diabatized to form two coupled diabatic surfaces. Quantum dynamics calculations are performed to obtain the fundamental frequencies and the energies of low lying bound states. Comparison of bound state energies with experimental values show good agreement. (C) 2003 American Institute of Physics.