Abstract: The invention relates to a heat exchanger (50) for a dosing unit of an SCR (selective catalytic reduction) exhaust gas treatment device (10), wherein an adjustable volume of a fluid can be discharged by a dosing unit into an exhaust gas system (177) of an internal combustion engine (155). The heat exchanger (50) has at least one fluid channel (52) through which air can flow, wherein said fluid channel (52) is routed around at least a subregion of an outer peripheral wall (54) of a dosing valve (34) of the dosing unit (100). In a further aspect, the invention relates to an SCR dosing unit (100) having a heat exchanger (50) according to the invention, wherein an air intake system (78) is arranged on the dosing unit (100), such that it is possible for air to be conveyed into the heat exchanger (50) during operation of the internal combustion engine (155).