The oxidation resistance and lubricating properties of graphite treated with magnesium phosphate were investigated. Magnesium-phosphate-treated graphite showed improved oxidation resistance. That is, with magnesium-phosphate treatment, the oxidation temperature of graphite increased by almost 200 degrees C. Furthermore, the friction coefficient of magnesium-phosphate-treated graphite measured at 500 degrees C was about 0.05, which was smaller than that measured at room temperature.