Polymer-free carbon nanotube fibers are spun from aqueous dispersions using a flocculation-based process that was developed. It produces hollow fibers, folded ribbon fibers, and solid fibers (see Figure). The fibers spun from single-walled nanotubes exhibit relatively high electrical conductivities (similar to 140 S cm(-1) at room temperature) and electrochemical capacitances (similar to 100 F g(-1)) after annealing. Fiber supercapacitors are made from the spun fibers.