In order to discuss the reactivity of carbonaceous materials with CO 2 , the Raman spectroscopy analysis was carried out. Nine kinds of materials were examined. The Raman spectra of ordered materials could be assigned to the graphite structure and its defect, but those of disordered materials could not. New parameters were derived to evaluate the structure of the latter. Using the parameters, the structure change was followed during high temperature heat treatment. The disordered material consists of random structure, graphite structure and its defects. The random structure changes to the graphite structure with many defects and the defects decrease with the heat treatment temperature. The reaction rate constant is evaluated. It increases when the structure changes from the random structure to the graphite structure with many defects. After the change, it decreases with decreasing the defects in graphite structure. Thus, the most reactive material should consist of the graphite structure with many defects.KEY WORDS: natural and synthetic graphite; coke; wood charcoal; bamboo charcoal; Raman spectroscopy; reactivity with CO 2 ; new parameters to evaluate structure; structure change during heat treatment; highly reactive material.