Nanostructured zinc oxide (ZnO) for gas sensing application has been prepared by using normal and oblique angle sputtering deposition techniques under different substrate temperatures. Oblique angle plasma beam deposition is demonstrated effectively growing large-area uniformly aligned and inclined ZnO nanorod arrays on catalyst-free silicon substrate due to a self-shadowing mechanism, whereas normal radio frequency sputtering deposition yields nanoparticles as island growth mode. Furthermore, the density of the nanorod arrays is dependent on the incident angle of ZnO plasma beam. With an increase of the incident flux angle, large inter spacing was induced, resulting in sparser nanorod arrays. The nanorod arrays grown with an incident angle of 70 have an average diameter of similar to 150-300 nm and length of similar to 700-750 nm. The experimental data from characterization of the samples indicates that the obtained samples at different substrate temperatures and incident angles have wurtzite structure with a c-axis orientation. Sensing characterization reveals that the nanorod-based sensor shows higher sensitivity, faster response and recovery time, as well as better reproducibility than that of nanoparticle-based gas sensor to 100 ppm hydrogen and methane at low operating temperature below 150 degrees C due to the porosity and large grain boundaries of the nanorod arrays. It demonstrates that oblique angle of sputtering deposition is a simple, inexpensive synthesis process to get high-porosity nanostructures and as a result, improves the sensing properties of fabricated ZnO sensors, which permits us to obtain sensors with high sensitivity, low operating temperature and stability. (C) 2011 Elsevier B.V. All rights reserved.