Electrospun isolated camphor sulfonic acid-doped polyaniline nanofiber sensors were fabricated and tested in the presence of various aliphatic alcohol vapors. Due to the large surface to volume ratio, uniform diameter and small quantity of active material used in the construction, these sensors are comparable to or faster than those prepared from nanofiber mats of the same polymer. Sensors made from individual fibers exhibit larger responses, especially for bigger alcohol molecules, and also show true saturation upon exposure and removal of the alcohol vapor. Interestingly, the response of sensors made from electrospun nanofibers to small alcohol molecules is opposite to that observed for cast nanofiber mats and could be related to the doping process used in the preparation of the polymer in either case. The results indicate that the size of the alcohol and the dopant counterion determine whether alcohol molecules are allowed to penetrate polyaniline and lead to an extended coil configuration. A faster response and the ability to selectively deposit isolated nanofibers using electrospinning makes this technique attractive in the fabrication of low cost and low power consumption rapid response sensors. (C) 2007 Elsevier B.V. All rights reserved.