A sulfur-carbon composite based on vapor-grown carbon fiber (VGCF) is synthesized for lithium/sulfur batteries by potassium hydroxide (KOH) activation and melt-diffusion strategy. The sulfur-activated VGCF (S-aVGCF) composites were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and N-2 adsorption/desorption measurements. It is found that VGCF treated by KOH activation is longitudinally opened and presents a porous structure, and sulfur is embedded into the pores of an aVGCF network-like matrix after a melt-diffusion process. The S-aVGCF composite cathode exhibits better electrochemical reversibility, higher active material utilization and less severe polysulfide shuttle than both a pristine sulfur cathode and a S-raw VGCF composite cathode because of excellent conductivity, and the fibrous and porous structure of the aVGCF matrix. (C) 2013 Elsevier B.V. All rights reserved.