A new powder-diffraction technique for very high temperatures is described, in which a thermocouple combines the functions of sample support, heating, and temperature measurement. This device is simple, compact and inexpensive, and has proved to be very reliable. The maximum working temperature depends on the thermocouple material, and is normally 1750° C using 5/20 rhodium-platinum, or 1850° C with 20/40 rhodium-platinum couples.