The abatement of nitrogen oxides from industrial and vehicular waste streams is a field of intense investigations since many years. Recently, the increased awareness of the scientific community and of the general public of the climate change issues has accelerated the pace of research in the field. The development of efficient and stable De-NOx catalysts is one of the main routes for the mitigation of NOx pollution. Among the many different De-NOx catalysts proposed so far, we focus on iron-containing zeolites, and on Fe-ZSM5 in particular.