In order to achieve a low-carbon operation of the blast furnace, it is important to promote not only the reduction of iron oxides but also the carburizing and melting of reduced iron. In this study, the use of highly reactive carbon-iron oxide composite was focused on. The effect of chemical species of silicon oxides which are main components of ash in coal and gangue minerals in iron ores on the carburizing and melting phenomena of iron was examined in detail. The silicon transfer to metallic iron was also thermodynamically investigated under the condition with low carbon activity in iron.The composites prepared by hematite reagent, carbonaceous materials and silicon oxides such as SiO 2 , CaSiO 3 and Ca 2 SiO 4 having different SiO 2 activity were heated up to 1 300°C under inert gas flow. The reduction, carburization and melting behaviors were examined.The silicon concentration of the reduced iron in the composite with high SiO 2 activity was high, while the carbon concentration was low. It was thermodynamically confirmed that silicon transfer precedes carburization of iron in the reduced carbon-iron oxide composite under high SiO 2 activity condition.