The Gothic period that begins in the twelfth century in the north of France brought many changes in the architecture of cathedrals and churches. This new style is mainly characterized by achievements in the use of stone and glass but it also represents a great change in the use of metal for the construction of medieval buildings. Several tons of iron or steel reinforcements such as clamps, chains and tie-rods were used for each of the largest churches of the French kingdom for this period. These elements are of great interest to study the evolution of technical processes involved in the production and transformation of iron all along the medieval times. Nevertheless, cathedrals were built over several architectural phases, modified and repaired with iron elements potentially added at any of the numerous steps of this long history. As there is often no stylistic evidence that allows differentiating between the metallic reinforcements from different periods, it is only by absolute dating that a chronology of these elements can be drawn. The aim of this presentation is to show how radiocarbon dating of iron can participate, by giving time points, to a multidisciplinary approach (archaeology, history, materials science) that tries to understand the work of craftsmen from the production of iron to the introduction of the ferrous artefacts in these medieval monuments. After a description of the iron radiocarbon dating protocol, we will present the dates obtained on ferrous elements collected in seven gothic cathedrals among the most important in the development of French gothic architecture. We will discuss the dating results against the archaeological study and the metallographic and chemical analysis of the ferrous alloys.