An accurate determination of the catalytic property of thermal protection materi- als is crucial to design reusable atmospheric entry vehicles. This property is deter- mined by combining experimental measurements and simulations of the reactive boundary layer near the material surface. The inductively-driven Plasmatron fa- cility at the von Karman Institute for Fluid Dynamics provides a test environment to analyze gas-surface interactions under effective hypersonic conditions. In this study, we develop an uncertainty quantification methodology to rebuild values of the gas enthalpy and material catalytic property from Plasmatron experiments. A non-intrusive spectral projection method is coupled with an in-house boundary- layer solver, to propagate uncertainties and provide error bars on the rebuilt gas enthalpy and material catalytic property, as well as to determine which uncer- tainties have the largest contribution to the outputs of the experiments. We show that the uncertainties computed with the methodology developed are significantly reduced compared to those determined using a more conservative engineering ap- proach adopted in the analysis of previous experimental campaigns.