The sensors based on ZnO tetrapods (T-ZnO) and ZnO tetrapods with TiO 2 mixing (T-TiZnO) and Au coating (Au/T-TiZnO) were investigated. The T-ZnO and T-TiZnO were synthesized by a simple thermal oxidation technique. The leg of the tetrapod is about 1–10μm in length and 160–500nm in diameter. Au coating was performed by sputtering technique and annealed at 550°C for 6h under normal atmosphere. The ethanol sensor response of the T-ZnO, T-TiZnO and Au/T-TiZnO sensors was tested at the operating temperature of 260–360°C with the ethanol concentration of 50, 100, 200, 500, and 1000ppm. It was found that at the optimum temperature the Au/T-TiZnO sensor exhibited the highest sensor response and the T-TiZnO sensor exhibited higher sensor response than that of the T-ZnO sensor. The Au/T-TiZnO sensor exhibited the highest sensor response up to 240 at 340°C under the ethanol concentration of 1000ppm. The enhancement of the sensor response based on the T-ZnO by TiO 2 mixing and Au coating can be explained by alloying effect and metal catalytic effect, respectively. The response enhancement can be explained in terms of electron concentration, n 0 in air and reaction rate constant, k Eth . The evidence for both effects can be found in higher sensor resistance in air and lower sensor resistance in the ethanol ambient.