In this paper, OpenFOAM was employed to numerically investigate syngas (H-2 and CO) production by the simultaneous splitting of H2O and CO2 via thermochemical redox cycle based on iron oxide (Fe3O4). The effects of operating conditions such as pressure, temperature and species reactant ratios on syngas yield were investigated. The results indicated that amount of syngas yield was highly dependent on the reduction temperature. It was found that the process at high pressure could lower the reaction temperature and increased species production rate. The overall syngas yield increased from 1.34% up to 98.65% when the pressure increased from 5 to 20 atm. The analysis of the results showed that the syngas yield and the syngas composition were strongly influenced by the ratio of H2O/CO2 (gamma(g)). The highest syngas purity (ratio of H-2/CO (gamma(s))) = 3.36 was reached at gamma(g) = 2. The optimum operating conditions for hydrogen-rich syngas production were obtained when gamma(g) = 2 under 1600 K at 20 atm. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.