Many carbon materials have desirable electrochemical, mechanical, electrical, and thermal properties that make them ideal candidates for dual-use energy-storage devices integrated into fiber-matrix composites or textiles. Commercial fabrics are cost-effective, scalable materials that are often fabricated specifically for composite applications. However, the electrochemical properties of these commercial materials are largely unknown. This study focuses on the properties of unmodified commericial carbon fabric materials for use in electrochemical devices such as lithium-ion batteries. Electrochemical capacity was evaluated for carbon fibers derived from a wide variety of grades of fabrics based on polyacrylonitrile (PAN), pitch, or activated carbon, and carbon papers made from carbon nanotubes or nanofoams. Double-layer capacitances were also measured for potential application to supercapacitors. The fiber microstructures were analyzed via X-ray diffraction and Raman spectroscopy. Nanofoam papers demonstrated the best overall electrochemical performance, with capacities consistently achieving 135 mAh/g after 50 cycles and capacitances of 5-7 F/g. but the mechanical properties were poor. IM7 and T300 PAN-based woven fabrics demonstrated the best potential for multifunctional use, with reversible-discharge electrochemical capacities as high as 158 mAh/g after 50 cycles and tensile strengths of 3-5 GPa, Removing the polymer sizing from PAN-based fibers did not appear to improve performance. (C) 2009 The Electrochemical Society.