The self-calibration of a fixed-point thermocouple should be performed in the operating environment of this thermocouple, e.g. in a calibration furnace. To get a clear calibration signal, the phase transformation point has to be passed as slowly as possible. With heating rates of 0.5 K/min, the transformation duration typically takes 5 minutes. Commercially available temperature controllers support the programming of such temperature ramps. Another way of producing a reproducible calibration signal is to alter the set temperature parameter very carefully, starting slightly below the phase transformation temperature. The requirements to be fulfilled by the measuring equipment are defined by the accuracy to be guaranteed. For precision thermocouples, a PC interfaced high-resolution digital voltmeter (0.1µV) is necessary. The recorded data signal has to be processed by means of special software for a graphically interactive or also automatic analysis.