Method and device for reducing the NO

x 22X X 2X 2The disclosure involves a method for reducing the content of NOand NO in gases. The method includes the conduction of a gas containing NO and NOover a series of two catalyst beds containing of one or more zeolites charged with iron followed by the: addition of a reduction agent for NObetween the catalyst beds. The first catalyst bed reaction zone is used to degrade the NO and the catalyst bed second reaction zone reduces the NOand breaks down at least part of the remaining NO. The inventive device comprises at least one radially traversed catalyst bed.