Needle coke, the remaining material after refining petroleum, is used as an anode of a lithium-ion secondary battery. Sulfur is separated from the needle coke to below 0.1 wt.% using the molten caustic leaching (MCL) method developed at the Korea Institute of Energy Research. The needle coke with high-purity is carbonized at various temperatures, namely 0, 500, 700 and 900 degrees C. The coke treated at 700 degrees C gives a first and second discharge capacity of more than 560 and 460 mAh g(-1), respectively, between 0 and 2.0 V By contrast, the first and second discharge capacity of untreated coke is over 420 and 340 mAh g-1, respectively, between 0.05 and 2.0 V. The first discharge capacity of 560 mAh g(-1) is beyond the theoretical maximum capacity of 372 mAh g(-1) for LiC6. Though the cycle efficiency is not consistent, the needle coke heat-treated at 700 degrees C persistently maintains an efficiency of over 90% until the 50th cycle, except on the first cycle. This study demonstrates that the needle coke with high-purity could be a good candidate for an anode material in fabricating high-capacity lithium-ion secondary batteries. (c) 2005 Published by Elsevier B.V.