Vanadium oxide nanotubes are prepared on a Si substrate with hydrothermal method in this experiment with dodecylamine serving as template. X-ray diffraction, Raman spectroscopy and scanning electron microscope (SEM) are employed to characterize the structural and electronic properties of these nanotubes. The results show that the growth of VOX nanotubes and their gas sensing properties are affected by the hydrothermal reaction time rather than mixing time. With longer reaction time, the VOX nanotubes display better properties with smoother walls, stronger gas sensitivity and faster response time (15 s), than with shorter reaction time. SEM results reveal that VOX nanotubes have inner diameters between 25-35 nm and outer diameters between 65-100 nm. The sample inner diameters vary between 25 and 35 nm. The outer diameters are also quite similar in all tubes and lie between 65 and 100 nm.