Within the research project “Stromboli”, the increase of the energetic efficiency of steelmaking in the electric arc furnace using a targeted injection of post-combustion oxygen was studied. For this purpose, a prototype of a temporal high-resolution extractive gas analysis system was developed, that allowed tracking the highly varying process conditions in the furnace off-gas. Based on these investigations and with the help of a dynamic mass and energy balance model, an optimized furnace operation was derived which, in the investigated case, led to a sustainable reduction of the electrical energy consumption of about 4 %.