For the development of highly sensitive NO 2 gas sensor, SnO 2 -based film was prepared using radio-frequency (RF) induction plasma deposition (IPD) method. It is first shown that the IPD process is possible to fabricate a gas sensitive film consisting of nanostructured particles supported by rather large particles by controlling several processing parameters of plasma deposition. The effect of processing parameters and annealing temperatures on the physical properties of SnO 2 thin films was examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) method. The sensor films were used to detect NO 2 gas at a concentration range from 20 to 200parts-per-billion (ppb), and the results show that the gas sensors have achieved high sensitivity at extremely low NO 2 concentration down to 20ppb with the response and recovery time less than several minutes.