Abstract: A device for generating a reducing agent gas from a solid or liquid reducing agent, where the reducing agent gas is preferably suited for nitrogen oxide reduction in an exhaust gas of a combustion engine, the device including a reactor with an inner volume and an inlet for a reducing agent solution and an outlet for the reducing agent gas. The device further including a heating system disposed at least partially in the inner volume and a heating control unit for controlling the heating system, wherein the inner volume includes first and second heating zones each including at least one heating element and controlled independently of each other by the heating control unit.