Uncertainty quantification and sensitivity analysis for a high enthalpy flow were per- formed using thermochemical nonequilibrium models of the air. Parameters of chemical kinetic rates and relaxation time for two-temperature model were chosen as input uncer- tainties. As a result of the uncertainty analysis, those input uncertainties do not have significant in uences on the convective heat ux for the present conditions. However, stan- dard deviation of temperature distributions has a different tendency between the models. Moreover, global sensitivity analysis using Sobol’ indices was performed, and it is found that sensitivities for temperature are strongly related to the forward reaction rates of O2 dissociation and the relaxation time of N2 molecules near the shock front, while the forward reaction rates of O2 and relaxation time of N2 are responsible for the sensitivity near the wall.