Alkaline treatment of Fe-ZSM-5 zeolite induces substantial intracrystalline mesoporosity and enhances the population of isolated Fe³⁺ at the expense of oligonuclear clusters. In situ UV/vis showed that this redispersion affects the redox properties of the alkaline-treated zeolite and leads to lower activity in direct N₂O decomposition compared with the parent sample. Subsequent ion exchange of the alkaline-treated sample in ammonium nitrate solutions induced a renewed alteration in iron speciation, resulting in a similar constitution as in the parent zeolite but with a higher concentration of Fe²⁺ sites able to activate N₂O. Mechanistic investigations in the TAP reactor furthermore affirmed that these newly obtained species had improved oxygen desorption, which correlates with the superior activity in direct N₂O decomposition.