Activated carbon fiber (ACF) containing Sn nanoparticles were prepared by impregnation and were investigated as a negative electrode material in lithium batteries. The tin particle size was controlled by selecting an ACF with an adequate surface structure. This Sn/ACF composite cycled versus Li metal showed a first discharge capacity as high as 200mAhg−1 compared to the pristine ACF which showed only 87mAhg−1. Excellent cyclability with these composites was obtained with ACF BET SSA as large as 2000m2 g−1 and 30wt.% Sn.