ZnO thin films were prepared by thermal oxidation of Zn metal at 400 degrees C for 30 and 60 min. The XRD results showed that the Zn metal was completely converted to ZnO with a polycrystalline structure. The sensors had a maximum response to H-2 at 400 degrees C and showed stable behavior for detecting H-2 gases in the range of 40 to 160 ppm. The film oxidized for 60 min in oxygen flow exhibited higher response than that of the 30 min oxidation which was approximately 4000 for 160 ppm H-2 gas concentration. The sensing mechanism was modeled according to the oxygen-vacancy model. (c) 2009 Elsevier B.V. All rights reserved.