Using nanostructure metal oxide decorated interfaces we study the conductometric response of PS to SO2 in a UHP N-2 flow and in the presence of xylene. We have evaluated the response of the porous silicon (PS) interface and the enhancement of the interface decorated with SnOx, NiO, CuxO, and AuxO (x >> 1) nanostructured deposits. SO2, which acts as a Lewis acid, appears to be rapidly converted upon interaction to form a basic analyte which interacts with the nanostructure decorated PS interface. This process can be monitored through the inversion of conductometric response. We suggest that SO2 interacts and forms the transient ion, SO3-. The process can be inhibited in the presence of xylene. The response of an SnOx and AuxO decorated interface to this suggested intermediate is found to dominate those of NiO and CuxO. (C) 2015 The Electrochemical Society. All rights reserved.