The electrospinning technique was utilized to produce camphorsulfortic acid (HCSA) doped poly(o-toluidine) (POT)-polystyrene (PS) composite fibers in the non-woven mat form. HCSA doped POT-PS composite fibers were fabricated on an interdigited gold (Au) substrate for use as a chemical vapor sensor. The composite fiber sensor responded to volatile chemicals in different ways, depending on the polarity of sensing chemicals. The surface morphology of the non-woven composite fiber mat after chemical vapor sensing was unchanged. This study highlights that composite fibers comprised of polyaniline derivative and a spinnable polymer do have potential for use as chemical sensors due to their good solubility in common solvents and detectable electrical changes at low fiber contents. (c) 2008 Elsevier B.V. All rights reserved.