Abstract: A device 1, capable of being placed in-line in the exhaust conduit of an IC engine upstream of an SCR catalyst, which produces a gaseous hydrolysis product, containing ammonia, which is added to the exhaust gas in a controlled manner to pass therewith through the SCR catalyst to reduce the NOx content of the exhaust gas. The device 1 has an inlet 2 and an outlet 3 for the exhaust gas flowing therethrough and comprises an outer body 4, which forms a pressure barrier, and passing through the outer body 4 is an inner body 5 which comprises a flowpath longitudinally therethrough from the inlet 2 to the outlet 3.