The combustion rate of a burning graphite rod in a stagnation flow of water vapor is measured experimentally as a function of the surface temperature, with the stagnation velocity gradient taken as a parameter. The combustion rate, which is obtained from the surface regression rate in the forward stagnation region and the density change in the test specimen, is then used to determine surface kinetic parameters for the global C-H2O reaction. Relative combustion rates for oxidizers (O-2, H2O, and CO2) are also examined, finding that H2O is a medium oxidizer even at high surface temperatures. It is also painted out that there is a possibility that the CO2 produced by the water gas shift reaction in the gas phase participates in the surface reaction as an additional oxidizer and enhances the combustion rate in H2O flow.