The effect of NiO additives and post-deposition treatment by rapid thermal annealing on the properties of TiO2 thin films has been studied. The structural, compositional and H-2 sensing parameters have been investigated by X-ray diffraction (XRD), glow discharge optical emission spectrometry (GDOES), scanning electron microscopy (SEM) and by electrical measurements. In the range of annealing temperatures from 500 degrees C to 700 degrees C crystallization started and the structure changed from amorphous to polycrystalline. The NiO modified sensing films exhibit enhanced and improved sensing behavior to hydrogen at relatively low operating temperatures. The inversion of the conductivity type of response due to different H-2 concentrations has been observed. The critical H-2 concentration causing break of the p-type response to n-type response was identified. The temperature dependence of this critical concentration as a function of operating temperature was studied. Moreover, change of response type due to different annealing temperatures was achieved. (C) 2012 Elsevier B. V. All rights reserved.