Multi-layered random network structure of titanium dioxides (TiO2) nanofibers was fabricated by calcining electrospun TiO2/PVP hybrid fibers. Their structural, electrical and gas sensing properties were investigated in a calcination temperature range of 400-800 degrees C. TiO2 nanofibers are polycrystalline with anatase structure below 600 degrees C and a mixture of anatase and rutile structures at 800 degrees C. The diameter of TiO2 nanofibers ranged from 350 nm to 500 nm, and the grain size increased from 8 nm to 45 nm with the increase in calcining temperature. The activation energies were in the range of 0.50-0.57 eV. The TiO2 nanofibers calcined at 600 degrees C showed the gas response upon exposure to CO concentration even below 1 ppm. (C) 2010 Elsevier B.V. All rights reserved.