A throttle-valve assembly (10) having a housing (12), which has a continuous throttle opening (16) through which a gaseous medium (62) can flow in a main flow direction (60), in which a throttle valve (20) fastened pivotably on a throttle-valve shaft (18) is arranged in the throttle opening (16), and the throttle-valve shaft (18) can be pivoted by an actuator (26) arranged in the housing (12), in which, starting from the axis of rotation (19) of the throttle-valve shaft (18) downstream along the main flow direction (60) of the gaseous medium (62), the throttle opening (16) has an approximately straight cylinder section (64) with a height H1 and a radius RZ and in which a spherical-cap section (68) adjoins the approximately straight cylinder section (64). To reliably ensure a finely graduated control of the gaseous medium (62) passing through the throttle opening (16) during operation of the throttle-valve assembly (10), the spherical-cap section (68) has a central point (80) which, starting from the axis of rotation (19) of the throttle-valve shaft (18) downstream along the main flow direction (60) of the gaseous medium (62), is displaced by a distance H2, with the spherical-cap section (68) having a radius RK which is approximately determined by the following equation: