In this paper, the isothermal oxidation of the indefinite chill (IC) roll is investigated by using a thermogravimetric analyzer (TGA) from 550 to 700 °C under dry and humid atmospheres. It is found that the oxidation kinetics follow a linear trend and the oxide scale consists of two layers after the oxidation in dry air but three layers in humid air above 600 °C. In dry air, the graphite is covered by the oxide scale above 650 °C. The water vapor accelerates the oxidation of the matrix and the graphite. The graphite is covered by the extension of the oxide scale above 600 °C in humid air. The as-treated samples are examined with SEM and XRD, while the kinetics is based on TGA results.