This short review article gives an overview of the use of several novel, metallurgical temperature sensors. These include the Feroplug, the Sigmaplug, the Templug and PETIT. Metallographic methods that utilise carbide segregation and the thickness of metal oxide scales that accumulate on steam boiler pipes are also introduced. Besides reviewing the various metallurgical sensors, emphasis has been placed on the Sigmaplug, which is a new, potentially patentable technique. A new application i.e. monitoring of temperature fluctuation and overheating/underheating, for an ‘old’ patented technique, the Feroplug, is also discussed in this article. New results on the Sigmaplug, some of which have not been published before, on this potentially patentable technique are presented in this article. Additionally, the latest results by the present group of authors on the use of metallurgy-related phenomena in stainless steels for temperature measurement are introduced. The Feroplug is an ‘old’ patented technique that was originally designed for the measurement of long-term average temperatures. Recently, attempts have been made to assess the possibility of using this technique for temperature fluctuation and overheating/underheating monitoring. Results on this topic are introduced.