In addition to 0.5–1 vol% CO, gas streams leaving the RWGS unit typically contain 10–25 vol% CO2 and 5–20% H2O (rest H2) [12,21,22]. Kinetic studies were conducted to investigate the influence of temperature and concentration of each gas component on the reaction rate. Based on the respective results, a kinetic model was developed to predict the conversions of CO and CO2. Finally, an adiabatic fixed reactor was simulated to determine the amount of a methanation catalyst needed for a typical household fuel cell system.