Pure SnO2 and SnO2 polycrystalline nanofibers doped with multiwall carbon nanotubes (MWCNTs) are synthesized by electrospinning followed by calcination in air at 500 degrees C. The measurement results by sensors fabricated from these fiber mats at steady state show that the n-type SnO2/MWCNT nanofibers are able to detect carbon monoxide at 50 ppm at room temperature, while the pure SnO2 nanofibers are insensitive up to 500 ppm. The MWCNT doped SnO2 nanofibers have demonstrated their potentials for wearable room temperature gas sensors with low cost and power consumption. (C) 2007 American Institute of Physics.