An integrated power switch structure comprises a lateral MOS transistor and a lateral or a vertical thyristor. The drain-to-source circuit of the lateral MOS transistor is in series with the cathode-anode circuit of the thyristor. In order to achieve the reliable switch on/off of the power switch structure at high dielectric strength and low on resistance, the invention at least insulates the source electrode of the lateral MOS transistor to the substrate by means of a buried oxide layer.