Crucible steel has fascinated scientists for over a century, but the study of its production is a fairly new field of research. Publications so far focus on archaeological sites from Central Asia (9th–12th centuries CE), India and Sri Lanka (mostly 17th century CE onwards). However, the development and spread of crucible steel-making is yet to be re-constructed to its full extent. It has been long suspected that the origins of this sophisticated technology potentially are to be found in Persia, modern day Iran, yet no archaeological evidence for this has been published so far. Several historical manuscripts provide some information on this technology and relate it to production centres in Persia. This article reports archaeological evidence for Persian crucible steel production, based on the medieval site of Chāhak in Central Iran, in the context of selected historical documents. The Chāhak crucible fragments have distinctive features that had not been seen elsewhere, while some similarities with Central Asian crucibles are evident. Microstructure and elemental composition of different crucible fragments and slags were determined with optical microscope and SEM-EDS, providing information on the fabric of the crucibles, the slag composition and the metal which was produced by this process. This project attempts to open a new chapter in the study of crucible steel production by introducing the Chāhak tradition, comparing it to other Central Asian traditions of production. This may pave the way to track and study the origins of crucible steel production in the broader context of Central and Western Asia.