Gas sensor system was designed and fabricated using micro-electro mechanical system (MEMS) technology, coating the nano-crystalline F-doped SnO2-based material as a micro-bead on a silicon substrate with Pt electrode and heater by screen-printing method. Gas sensing properties of the sensor were tested against combustible gases like H2, CO, CH4, C3H8. Nano-crystalline F-doped SnO2 micro-sensor showed maximum sensitivity for hydrogen gas and little sensitivities for other gases at a heater voltage of 0.7V. The present micro-sensor showed higher sensitivity and better stability for hydrogen gas in comparison to commercially available SnO2, and is a low energy consuming portable sensor module that can be mass-produced with nano-crystalline gas sensing material using MEMS technology.