We present the results of investigations of thin-film hydrogen sensors that show high sensitivity at low operating temperatures. These hydrogen sensors are manufactured using the sol-gel technique which ensures high temperature stability of nanocrystalline grains in the SnO2 films. It was established that the highest sensitivity of the sensors occurred at 100-130 degrees C. The hydrogen Sensitivity depends on the hydrogen concentration linearly starting at 50ppm, and reaches 10(4) at 5000ppm. The response time was measured at 1-2s and the times were less than 10s. We show that compared to constant power supply, pulse heating of the sensor improves the stability of the sensor, reduces the sensitivity to humidity, and reduces performance drift. We consider the effects of the material substrates, technology of the comb-like electrodes, and catalyst preparations. Various possibilities of reducing CO gas cross sensitivity are also presented. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.