Rapid changes in a re-entry flowfield particularly at the bow shock wave, expansion corners, and neck regions can induce thermo-chemical nonequilibrium in the flowfield. Thermochemical non-equilibrium has significant effect on the aerothermodynamics of re-entry capsules. In the present paper, we investigate the non-equilibrium effects in Fire II re-entry flowfield. The re-entry flowfield is computed using five species (N2, O2, NO, N, O) and three dissociation and two exchange reactions. Two temperature model of Park is used to account for the vibrational non-equilibrium. Further we study the reactions that are effecting the gas composition in the flowfield. We find that thermo-chemical non-equilibrium brings changes in gas composition at the bow shock wave and first expansion corner. The gas chemistry in the separation bubble is frozen.