In this Letter, non-equilibrium rates of Zeldovich reactions N-2(i) + O reversible arrow NO + N reversible arrow O-2(i) + N reversible arrow NO + O in shock heated air flows are studied on the basis of state-to-state vibrational distributions. The comparison of reaction rate coefficients computed using state-to-state and thermally equilibrium vibrational distributions behind shock waves and different state-specific models for exchange reactions is presented. Reaction rates are calculated for various conditions before a shock front including a particular case of vibrationally excited free stream molecules. An essential influence of initial vibrational excitation of reactants on reaction rates behind a shock wave is shown. (C) 2015 Elsevier B.V. All rights reserved.