Detection of ethanol-gas has gained a lot of importance, especially in the determination of liver function in humans. It is also necessary in the food industries in safety control procedures. However, minute levels of ethanol-gas (in ppb) get released from the skin. An extremely sensitive and selective sensor with low limit-of-detection (LoD) capability is needed to detect the low concentration of ethanol-gas, even in the atmospheric air. With excellent electrical properties like low electronic noise, high surface area to volume ratio, high mobility, graphene can be of great choice for sensing single molecules¹. However, graphene sensors are not highly selective for any specific gas. Alternatively, Tin metal oxides acts as a highly selective material in sensing ethanol-gas². However, only 100 ppm LoD could be achieved at 170 ºC. Addressing this lacuna, we have fabricated a graphene sensor functionalized with tin oxide nanoparticles as an olfactive receptor to enhance the sensitivity towards ethanol-gas. We have also realized a LoD of 100 ppb Ethanol-gas sensing in the presence of air with the tin-oxide based graphene sensor.