Abstract: A converter for a device for supplying ammonia (NH3) into the exhaust gas flow of a combustion engine comprising a pressure-tight reaction vessel 2 for generating NH3 by heating a substance thermolytically separating NH3 under the effect of heat, and a heating unit 10 for heating the reaction vessel 2 to the operating temperature for generating the NH3, is defined thereby that the reaction vessel 2 usefully comprises in the region of its bottom an outlet 4 provided with connection means and an inlet 3, spaced apart from the outlet 4, also provided with connection means, with which connection means the interior of the reaction vessel 2 is connectable to a filling and withdrawal unit 13 for drawing off a carrier medium disposed in the reaction vessel 2, and for filling the reaction vessel 2 with new substance thermolytically separating NH3 transported by the carrier medium.