The potential for using superposition to predict the response of resistive-type gas sensors when they are exposed to more than a single gas was tested using two SnO2-based sensors. It is proposed that the selectivity of resistive-type gas sensors could be improved, or individual gas concentrations extracted, based on the observed response values of the sensors and a mathematical formulation. In this study, the behavior of several resistive gas sensors was tested in a mixed-gas environment of toluene and acetone, using a GASENTEST, which is an automatic gas sensor testing machine developed for this study. The measured responses were compared with calculated responses based on our mathematical formula. Additionally, the actual concentrations of the input gases were compared to the gas concentrations calculated from the observed response of the sensors. (C) 2016 Elsevier B.V. All rights reserved.