The thermoelectric power of several refractory thermocouples was investigated, W‐Ta for temperature measurements up to 3000°C, W‐Mo up to 2600°C, Ta‐Mo up to 2600°C and W‐W/Mo (alloy 50 percent Mo/50 percent W) up to 2900°C.Basic calibration was carried out using several melting points and the results were verified and interpolated by means of an optical pyrometer.The couples W‐Ta and W‐Mo have been applied in this laboratory to the temperature measurement requirements in high temperature vacuum furnaces and determinations of spectral emissivity.