Fe-Ba/ZSM-5 catalysts were prepared for NO + O-2 adsorption and NO reduction by CO at 250-400 degrees C. NO adsorption and reduction were investigated for different Fe contents, while the Ba content was fixed at 5 wt.%. The catalysts were characterized by BET, SEM, XRD, XPS, H-2-TPD, and in situ DRIFTS. The NO + CO activity tests of Fe-Ba/ZSM-5 catalysts showed that the NO reduction efficiencies were strongly affected by temperature. The NO adsorption capacity of Fe-Ba/ZSM-5 catalysts increased with increasing Fe loading. The results of catalyst characterization showed that the dispersion of Fe species is one of the most important factors affecting NO reduction and adsorption performance. High Fe loading increased the amount of adsorbed NOx, while the NO + CO reaction was favored by good dispersion of Fe species. However, the NO adsorption capacity decreased for Fe loadings above 8.3% due to the aggregation of metal oxides. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.