A new type of micro catalytic combustible gas sensor system was designed and fabricated using micro-electro mechanical system (MEMS) technology. A chemical vapor deposition (CVD) method is used to coat porous nano-crystalline SnO₂ catalyst layer. Tin chloride anhydrate vapor was used as the precursor, and it reacted with ammonium sulfide [(NH₄)₂S] to form tin disulfide (SnS₂) nanoparticles. The tin disulfide was dried up, annealed in air, then it transformed into polycrystalline SnO₂ nanoparticles. The X-ray diffraction (XRD) measurement was used to investigate the structural properties of the SnO₂ films. The morphology of the samples was investigated by field-emission scanning electron microscopy (FESEM). X-ray photoelectron spectroscopy (XPS) provided the information on chemical composition of the SnO₂ films. The sensing elements and the reference elements were connected to a Wheatstone bridge circuit for the measurement of gas-sensing properties. The catalytic combustion sensor exhibited relatively higher sensitivity (75.4 mV/1% H₂) and good linearity (99.4%) to H₂ from 0 to 4% V/V. The response and recovery times to 4% H₂ were 0.65 s and 2.32 s, respectively. Finally, the sensor signal was very stable during a 200 d long term operation (accuracy＞95%). It was noteworthy that the nano-structured SnO₂ as catalyst film in a catalytic combustible gas sensor could considerably improve the performance of the gas sensor. It can be used in realizing portable sensing devices such as hydrogen analyzers and hydrogen leak monitors.