The present invention relates to the use of solids consisting of a metal-organic framework (MOF) and having the units of the following formula (I): MmOkXILp as a nitrogen-oxide catalyst. The present invention also relates to devices for enabling the implementation of said use. The nitrogen oxides in question are nitrogen monoxide and nitrogen dioxide, collectively referred to as NOx. The MOF solids of the present invention are advantageously capable of removing nitrogen oxides from a liquid or gaseous effluent, for example from water, from the exhaust gases of a vehicle, factory, workshop, laboratory, stored products, urban air vents, etc., without any reducing agent and at a low temperature. The DeNOx catalysis is a major issue for our societies. The invention can be used for reducing or even avoiding the consequences for public health of the toxic NOx gases resulting from human activity.
