Pure and KCl-doped TiO(2) nanofibers have been synthesized by electrospinning and calcination technique. The measurement results by the sensors fabricated from these fibers at the working electrodes show that KCl-doped TiO(2) nanofibers hold the improved humidity sensing properties with the resistance varying more than four orders of magnitude in the range of 11%-95% relative humidity, while the resistance of pure TiO(2) nanofibers changes only about two orders of magnitude. An ion-controlled model has been established to explain the results further. Additionally, excellent sensing characteristics (rapid response and recovery behavior and good stability) have been also found based on KCl-doped TiO(2) nanofibers, which endows our product with the potentials for humidity sensors. (C) 2008 American Institute of Physics.