In this work, a new method for the synthesis of polyaniline (PANI) nanotubes was presented. Experimentally, Mn2O3 nanofibers prepared by electrospinning technique were used as the oxidant template to initiate the polymerization of aniline in acid solution. After reaction, polyaniline shells were formed on the Mn2O3 nanofiber surface, and the Mn2O3 nanofibers were spontaneously removed. As a result, PANI nanotubes were obtained. As-prepared PANI nanotubes show an average diameter of 80 nm and inner diameter of 38 nm. The final PANI nanotubes were characterized by SEM, EDX, TEM, FTIR and XRD. The gas sensing of as-obtained PANI nanotubes was also investigated. It was found that the PANI nanotube sensing device could detect as low as 25 ppb NH3 in air at room temperature with good reversibility. (C) 2010 Elsevier B.V. All rights reserved.