The expanded graphite (EG) could be prepared rapidly by microwave irradiation for graphite intercalation compounds (GIC). GIC was prepared through the chemical intercalation of natural flake graphite and concentrated sulphuric acid

and potassium permanganate was added as oxidizing agent in the progress. GIC samples would show different color and luster with potassium permanganate augmenting. For graphite flakes whose granularity was more than 0.42 mm

the biggest volume expansion was 285 ml·g-1 when the mass ratio is m(graphite):m(H2SO4):m(KMnO4)=5:10:4. The achieved EG particles were coarse and long. The dosage of potassium permanganate would decrease with graphite flakes size increasing when it reached the biggest volume expansion

the achieved EG particles also would turn more slender. The optimal radiant time was 30—60 s

the achieved EG worm was scorched partly in excess radiant time. In the process of microwave irradiate GIC

30%—35%(mass) GIC would be lost.