Abstract. A series of Fe/Ga-ZSM-5 catalysts with different Ga contents were prepared by solid-state ion exchange method. Ultraviolet and visible Raman spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, H2-temperature-programmed reduction, and N2O decomposition at 523 K were used to investigate the effect of extra-framework Ga on the nature of the Fe species in Fe/Ga-ZSM-5…