Anovel microelectronic device utilizing the gas sensing properties of tinoxide SnOx and electrical properties of plasma enhanced chemical vapor deposited (PECVD) diamondfilm for oxygengas sensing at higher and wide temperature range is presented in this paper. The sensor is fabricated as a layer of catalyst/SnOx(adsorptive oxide)/i(intrinsic)-diamond/p+-diamond CAIS structure. The performance of the new microelectronic gassensor has demonstrated a large sensitivity to oxygengas. The response is reproducible and repeatable. Activation energy of oxygen adsorption by the new microelectronic gassensoris low. The sensor has also indicated CO detection in air ambient.