Coke samples excavated from LKAB's Experimental Blast Furnace (EBF) at MEFOS in Luleå, Sweden were used to observe the influence of in-furnace reactions on the changes in chemical stracture of cokes and their influence on kinetics of CO 2 reactivity. In addition to growth of carbon crystallite of coke, alkali concentration particularly potassium and sodium were found to increase as coke descended towards lower part of the EBF. The increase in carbon structure could be linearly related to measured temperature profiles of EBF. Isothermal and non-isothermal TGA measurements are shown to indicate that CO 2 reactivity of coke becomes progressively faster as it moves towards lower part of blast furnace. The study suggests that alkali enrichment of cokes in an operating blast furnace could have a strong catalytic effect on the CO 2 reactivity. Further research is expected to clarify the mechanisms of influence of coke minerals on reactivity and their implications in a blast furnace.