Herein disclosed is an induction cooking/warming appliance wherein an induction coil is located below a vessel supporting means, such as a counter. The counter may have a passage therethrough for the transmission of light, or it may be a solid body of transparent or translucent material. A double-walled vessel for containing food to be cooked or warmed is provided. The vessel is supportable on the counter. An inner wall of the vessel is inductively heated by a main magnetic field produced by the induction coil; but, an outer wall of the vessel, which is in contact with the counter on which the vessel is supported, is not inductively heated. Moreover, the outer wall of the vessel transmits light. Included within the vessel between the two walls thereof is a temperature detection unit which includes a temperature sensor unit arranged for sensing the temperature of the inner wall of the vessel and means responsive to the magnetic field produced by the induction coil for energizing an LED to produce light pulses at a rate corresponding to the temperature sensed by said temperature sensor unit. These light pulses are transmitted through the outer wall of the vessel and either through the counter or through a passage in the counter to a temperature receiving unit which includes a photodetector which is instrumental in developing a signal representative of the temperature of interest. Various embodiments of the vessel and the components thereof are disclosed.