a method for providing a reducing agent - containing gas flow in the exhaust system of an internal combustion engine includes providing at least one reducing agent precursor , evaporating the precursor to provide a gas flow , at least partially heating the gas flow to temperatures of at least 250 ° c ., at least partially converting the precursor in the gas flow to a reducing agent and adding the reducing agent - containing gas flow to the exhaust of the engine . the method and a device provide a reducing agent - containing gas flow in a quantity being easily controllable and adaptable to dynamic changes especially in exhaust systems of mobile applications such as automobiles . a temperature of a first zone is kept at 150 ° c . or just below while a temperature of a second zone is kept at more than 300 ° c . a hydrolysis catalytic converter is hardly cooled upon receiving the precursor as a vapor , positively affecting the method .