The present study investigates the chemical evolution of the burned gases in a first-stage nozzle operated under high inlet temperature and pressure conditions as they are foreseen for next-generation high-efficiency gas turbine machinery. Coupled aerothermochemical simulations are performed up to the extreme case of stoichiometric combustion without ulterior dilution. The intent is to provide an estimation of possible consequences arising from the residual reactivity of gases downstream from the combustor. These consequences might affect the future design of the expansion path in order to render nonstationary chemistry compatible with aerodynamics, energetics, and environmental aspects.