The low-temperature expandable graphite was successfully prepared with perchloric acid, phosphoric acid and KMnO4 by chemical process. The optimum weight ratio of perchloric acid to phosphoric acid in mixed acid was 1:0.2, and the weight ratio of the mixed acid, KMnO4 and natural flake graphite was preferably 1.5:0.1:1, The expanded volume can reach 260 mL/g at a relatively low temperature of 300 degrees C. Meanwhile, the prepared samples were characterized by means of Fourier transform infrared, thermogravimetry-differential scanning calorimetry and X-ray diffraction. (C) 2007 Elsevier Ltd. All rights reserved.