The present invention relates to a clock supervision unit (100) and an electronic system clocked by at least one clock (c*) and using the clock supervision unit (100). The clock supervision unit (100) analyzes the at least one clock (c*) based on a monitor clock (m*) provided together with the at least one clock (c*) or separately to the clock supervision unit (100). The clock supervision unit (100) at least comprises an activity unit (210), a deviation unit (220) and an auxiliary clock generator (240). The auxiliary clock generator (240) outputs an auxiliary clock (a*). The activity unit (210) detects the presence of the monitor clock (m*) based on the auxiliary clock (a*) and the presence of the auxiliary clock (a*) based on the monitor clock (m*). The deviation unit (220) detects clock faults in the monitor clock (m*) based on the auxiliary clock (a*). With the clock supervision unit (100) according to the present invention, the at least one clock (c*) can be supervised in more detail and it is possible to react on different clock faults in the at least one clock c* with different error handling procedures, e.g. by initiating a shutdown of the devices controlled by the electronic system.