The mechanism for VOC detection on SnO at room temperature is challenging to establish experimentally and is therefore not described in detail in the available literature. Chemiresistive MOX sensors are typically considered in terms of an oxygen-mediated process, devised in 1962 by Seiyama et al. . This route typically assumes a high temperature of operation to achieve oxygen radicals, or charged oxygen species at more moderate temperatures. This mechanism has received broad adoption due to its prevalence at high temperature and for noble metal decorated MOX systems, catalyzing oxygen ionisation . However, it may not be generalizable to room temperature processes. Alternative mechanisms have been proposed, including water-mediated routes, and direct adsorption with charge exchange. Water-mediated routes have been demonstrated at room temperature on Fe2O3, depending on the formation of hydroxyl groups mediating the charge exchange . Similarly, direct adsorption and charge exchange have also been proposed to explain the electron withdrawal of NOx on MoS2 at room temperature . The response of SnO to various reducing gases in this work was conducted using a humidified nitrogen gas flow. The sensing mechanism is unlikely to be oxygen mediated, as the nitrogen gas flow would provide no oxygen to restore those consumed on the MOX surface, and no significant drift between measurements was observed. Similarly, no significant dependence on humidity was observed. Consequently, the interaction between analyte gases (methanol, ethanol, isopropanol, acetone, and water) and SnO surfaces is expected to be an adsorption/charge exchange-based process.