Pure and NiO-SnO2 nanofibers are synthesized via a simple electrospinning method, and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The sensor fabricated from 5 mol% NiO-SnO2 nanofibers exhibits improved and excellent sensing properties to ethanol at 300 degrees C. The response is up to 25.5 when the sensor is exposed to 100 ppm ethanol. The response and recovery times are about 2 and 3 s, respectively. The linear dependence of the sensitivity on the ethanol concentration is observed in the range of 5-500 ppm. Good selectivity is also observed in our studies. These results make NiO-SnO2 nanofibers good candidates for fabricating practical ethanol sensors.