A furnace with a tungsten coil as the heating element has been designed and built for use with the X‐ray diffraction spectrometer in the study of phase changes and equilibria at high temperatures. Tests indicate that temperatures up to 2000°C. can be reached and maintained for long periods of time in a neutral atmosphere. Materials which are not readily affected by the tungsten vapors that are present can be heated successfully in this type of furnace. Summary With this furnace, samples may be heated to and held at temperatures up to 2000° C. while X‐ray spectrometer data are obtained. Phase changes and equilibrium conditions existing at temperatures considerably above those obtainable with Pt alloy elements and at different time intervals at constant temperatures can thus be readily and positively determined. It should be noted, however, that materials which are readily reduced by tungsten vapors cannot be satisfactorily heat‐treated in this particular type of furnace.