Abstract: A system is disclosed for determining the temperature of a cooktop having an upper surface and a lower surface. At least one controllable energy source is located below the lower surface of the cooktop to heat the area above the energy source on the cooktop, and at least one sensor with at least one detector to detect infrared radiation from the cooktop above the energy source. The level of infrared radiation is representative of the temperature of the cooktop, which may be glass ceramic. The sensor provides a signal indicative of the temperature of the cooktop which is then used to control the energy source in order to protect the cooktop from extreme temperatures. The signal may be alternatively utilized to provide an indication of a hot cooktop surface after the energy sources have been turned off. The signal optionally is also utilized to provide automatic control of the energy source to maintain a predetermined temperature, or to prevent exceeding a maximum temperature.