Archaeological research at Hoeke, a Late Medieval outer harbour of Bruges (Belgium), has revealed large quantities of iron slags, fuel and other remains of iron working. Archaeometrical study has provided an enhanced insight into the historic iron working process, a craft activity which had up till now remained completely unknown in one of the largest economic hubs of medieval Europe. Several petrological, mineralogical and geochemical analytical methods have been applied for this purpose. The metallographic analysis was performed using reflected light optical microscopy, while the mineralogical composition of the slags was characterized X-ray Diffraction (XRD) Spectrometry. Macroscopic identification of plano-convex bottom slag and hammerscales, combined with the geochemical data pointed out that the examined slag is indicating smithing activity, while no traces for iron ore melting were discovered.