Process for desulfurization of a nitrogen oxide storage catalyst

The invention relates to a process for desulphurizing a nitrogen oxide storage catalyst (3) disposed in the purification system of exhaust gas from an internal combustion engine (1), in particular a diesel engine used in motor vehicles, in conjunction with a particulate filter (4) .According to the invention, the desulfurization is carried out in that the nitrogen oxide storage catalytic converter (3) is placed to a temperature above a predetermined minimum temperature desulfurization and alternately repeated several times, between an oxidizing composition and a reducing composition of the exhaust gas, being performed, desulfurization subsequently being carried out at a regeneration of the particulate filter (4 ).