Most low-CO2 cements use ground-granulated blast-furnace slag (GGBS), a Ca-Mg-Al-Si-glass generated as a by-product from iron-making. However, this resource is to become scarce in Europe with the transition of steel industry towards electrified production using directly reduced iron (DRI) and electric arc furnaces (EAF). Vitrification of the new EAF-slags will make them usable as cementitious material similar to GGBS. These new slags, are likely to contain higher amounts of Fe and V than traditional GGBS. The incorporation of Fe in the glass-network will affect its cementitious reactivity, depending on amount, redox state and other ions present. The presence of trace metals such as V represents a further hindrance to cementitious reactivity and their leaching behavior depends on their role in the glass network. Here, we propose to use XANES measurements in combination with µ-XRF to clarify the distribution and speciation of Fe and V in complex, synthetic, slag-glasses with compositions