The increasing public concern on environmental issues prompts the use of clean energy in the iron and steel industry to reduce carbon dioxide (CO2) emissions. As a result, hydrogen (H-2) is introduced to replace a part of carbon monoxide (CO) as reductant for iron oxide reduction in revolutionary ironmaking industrial processes. The reaction kinetics between the CO-H-2 mixture reducing gas and the corresponding single components is important to optimize the operation and improve the efficiency of the industrial process; however, their relationship is poorly understood. This work presented the simulation of wustite reduction controlled by external gas diffusion in a thermal gravimetric analyzer. Innovative analogous circuit methods were for the first time used to analyze the reaction kinetic data. Six models (four were based on the combined method, and the other two were based on the individual method) were established to evaluate the relation of reduction rates between the CO-H-2 mixture and its individual components. Compared with other models, the I-S-P model generated the closest predictions with the experimental measurements, and the maximum relative error for this model was <8.5% under the present experimental conditions. Furthermore, the nonlinear relationship caused by the CO H-2 interaction was discussed and quantitatively addressed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.