One of the most extraordinary properties of the graphene, the high sensitivity to the adsorption/desorption of gas molecule, is still at the very beginning of its exploitation. The ability to detect the presence even of a single interacting molecule relies on the two-dimensional nature of graphene, that allows a total exposure of all its atoms to the adsorbing gas molecules, thus providing the greatest sensor area per unit volume. Nevertheless, due to the complexity of the entire process, starting from the graphene synthesis and/or isolation up to the introduction into the proper device architecture, the fabrication of the single graphene flake based chemical sensor is still challenging. Herein a simple approach to fabricate a sensitive material based on chemically exfoliated natural graphite is presented. The devices were tested upon sub-ppm concentrations of and show the ability to detect this toxic gas at room …