The invention relates to an ablation apparatus for intracardiac treatments which comprises a high-frequency source whose power output is controlled in a power-or temperature-controlled mode. Ablation catheters which each comprise at least one energy-emitting pole can be used with the apparatus, the or each pole comprising at least one temperature sensor for measuring the temperature of a tissue. The temperature sensors of the poles are either thermistors or thermocouples. The instrument further comprises a sensor-detection system and corresponding devices by means of which the power output can be automatically regulated such that the power is regulated according to the actual catheter type. To that end, it is not necessary to use a specially coded catheter and no special manual operations are necessary for adjusting the catheter type.