Summary: Thin fibers were spun from a colloidal solution of single-walled carbon nanotubes (SWNTs) using an electrophoretic method. Sodium dodecylbenzenesulfonate (NaDDBS) was chosen as a surfactant and showed good performance owing to its special chemical structure. The highest spinning velocity reached 0.5 mm s−1. The resulting SWNT fibers had a tensile strength of 400 MPa and a conductivity of 355 S cm−1. Their mechanical and electrical properties were markedly improved after adding NaDDBS as the dispersant in water.