Silicon/carbon composites were prepared at room temperature by dehydration of a mixture of sucrose and silicon powders using concentrated H2SO4, and the electrochemical behavior of this kind of material as an anode for lithium secondary batteries was investigated. The composites demonstrated a high initial coulombic efficiency of 82 % and a large charge capacity above 560 mAh g-(1) over 75 cycles. The improved electrochemical characteristics are attributed to the uniform distribution of silicon particles in an amorphous carbon matrix, which, to a certain extent, could buffer the volume change during cycling. (c) 2005 The Electrochemical Society. All rights reserved.