Abstract: A plurality of electrodes are positioned at the distal end of a catheter such that the electrodes may be positioned proximal biological tissue. A select number of the electrodes have a temperature sensing device associated with them for providing a temperature signal indicative of the temperature at the interface between the electrode and the tissue. A generator operates under the control of a processor to apply power to each of the electrodes. The power has an associated phase angle and, within a time duration, a plurality of alternating on periods and off periods, one set of adjacent on and off periods defining a duty cycle. The processor is programmed to determine the temperature at the electrode/tissue interface based on the temperature signals, compare the temperature to a target temperature and to adjust the power to the electrode accordingly.