Abstract: Water or other fluid is rapidly heated and supplied by micro-wave radiation on demand and at a preset and desired temperature by the invention herein. There is provided a chambered conduit serving as a reservoir for fluid therein and passing therethrough and of low volumetric capacity such as in the shape of a flat cylindrical tube. Subjection to micro-wave radiation of the full area of the chamber and penetration thereof throughout the full contents enables the transfer of micro-wave energy to the contents uniformly, equally and simultaneously for rapid and safe heating. The chamber is provided with conductive plates energized by a high frequency voltage generator and with a thermally controlled switching device to control the temperature of the fluid contents by directing and terminating the production and supply of micro-wave energy to the conductive plates.