Abstract: An emergency ignition device for thermal engines with controlled ignition comprises an oscillator connected to a stabilized electrical supply and whose output is connected to a power transistor connected in series with the primary winding of the ignition coil. A normally open control switch is closed at the same time as the starter is actuated. Means are provided for modifying the operational frequency of the oscillator depending on whether the control switch is open or closed, so that the oscillator operates at a first relatively low frequency as long as the control switch is closed and at a second frequency higher than the preceding one when the switch is open. A time delay circuit is connected to the oscillator and the control switch so as to inhibit operation of the oscillator during a predetermined period of time after the instant of closure of the control switch.