ZnO wire-like thin films were synthesized through thermal oxidation of sputtered Zn metal films in dry air. Their nanostructure was confirmed by SEM, revealing a wire-like structure with a width of less than 100 nm and a length of several microns. The gas sensors using ZnO wire-like films were found to exhibit excellent H2 gas sensing properties. In particular, the observed high sensitivity and fast response to H2 gas at a comparatively low temperature of 200 oC would lead to a reduction in the optimal operating temperature of ZnO-based H2 gas sensors. These features, together with the simple synthesis process, demonstrate that ZnO wire-like films are promising for fabrication of low-cost and high-performance H2 gas sensors operable at low temperatures. The relationship between the sensor sensitivity and H2 gas concentration suggests that the adsorbed oxygen species at the surface is O..