The invention relates to an electric machine (10), particularly a generator or a starter generator for a motor vehicle, comprising a converter (64) which is arranged on a cooling element (53) and composed of semiconductor switching elements (58, 59) actuated synchronously with the phase frequency for rectifying a generator alternating voltage or supplying a motor from a DC voltage source (61). According to the invention, the cooling element (53) has a base plate (55) and cooling fins (54), wherein the ratio of the surface wetted by coolant to the volume of the cooling element (53) ranges from 0.5 to 1.5 [l/mm], preferably from 0.8 to 1.0 [l/mm].