Titanium dioxide nanofibers were synthesized using electrospinning technique. The nanofibers were porous with an average diameter and length of similar to 150 nm and 200 p,m, respectively. Humidity-sensing devices were fabricated by lithographically defined aluminum electrodes on top of the nanofibers deposited on silicon dioxide grown thermally on a silicon substrate. The performance of a TiO2 nanofiber humidity sensor was tested by AC and DC electrical measurements at 40-90% relative humidity. The response and the recovery time were 1 s and 4 s, respectively, between 40% and 90% relative humidity. The sensitivity of the TiO2 humidity sensor in the range of 40-90% RH was 150 M Omega/%RH and 20 M Omega/%RH at 10 Hz and 100 Hz, respectively. The excellent sensing characteristics are attributed to the porous nature and the small diameter of the nanofibers. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.