Thermoelectric power is the magnitude of an induced thermoelectric voltage in response to a temperature difference across a material. The thermoelectric power of metal alloys is strongly influenced by the presence of solute atoms. Measuring thermoelectric power is therefore an accurate technique for characterizing the microstructure evolution of alloys taking place during various phase transformations. The potentialities of this technique are illustrated through four examples: (i) the measurement of copper solubility limit in iron; (ii) the characterization of the strain ageing kinetics of extra-mild steels; (iii) the determination of precipitation kinetics of MoC in low alloyed steels; and (iv) the monitoring of ageing of neutron irradiated power plant steels.