Fe n+ -ZSM-11 zeolites, with Fe 2+ and/or Fe 3+ as active sites prepared by us by reproducible post-synthesis methods showed magnetic properties. Otherwise, they are very important in environmental catalysis for the reduction of NO x to N 2 with hydrocarbons. The magnetic and catalytic properties of Fe-ZSM-11 samples with different contents of Fe 2+ and Fe 3+ were compared. The Fe 2+ -ZSM-11 sample (with 1.8 Fe 2+ per unit cell) showed the best catalytic activity and greater saturation magnetization than the other samples. The proportion of Fe 2+ per unit cell allows having higher amount of active sites for the reduction of NO when Fe 2+ is bonded to the zeolite structure. These Fe 2+ species bonded to the framework could generate ferromagnetic couples conferring the ferromagnetic behavior to the samples. The saturation magnetization of the other samples is smaller due to the lower amount of couples Fe 2+ –Fe 2+ . When the amount of Fe 3+ increases, the Fe bonded to the structure as counter ion decreases, forming α-Fe 2 O 3 as isolated clusters inactive for the reduction of NO. Mössbauer characterization of Fe 2+ -ZSM-11 showed that the Fe is forming couples (ferromagnetic) in an important amount. XANES studies of Fe n+ -ZSM-11 samples were performed in order to obtain the Fe 2,3+ composition.