In gasification processes, char-H2O and char-CO2 are the main heterogenous reactions that are responsible for carbon conversion into H-2 and CO. These two reactions are generally looked at independently without considering interactions between them. The objective of this work was to compare kinetics of each reaction alone to kinetics of each reaction in a mixed atmosphere of H2O and CO2. A char particle was gasified in a macro thermo gravimetry reactor at 900 degrees C successively in H2O/N-2, CO2/N-2, and H2O/CO2/N-2 atmospheres.