ABSTRACTSensors and Transducers, and in the specific context of this paper gas sensors, are currently amongst the largest growth areas in the modem electronics industry and this seems likely to continue for the foreseeable future. Nanocrystalline materials posses many properties that could make them ideal as potential gas sensing elements with many advantages over their microcrystalline counterparts. Most importantly these include increased surface area coupled with reduced sintering temperatures and times. However, it should also be noted that there are several disadvantages including the comparatively high cost of materials and increased electrical resistance.This paper reviews the operating mechanisms of semiconductor gas sensors and the possible advantages of using nano sized powders to produce gas sensitive devices. Results are presented which have been obtained from several materials produced by laser evaporation including alumina (Al₂O₃), zirconia (ZrO₂), and tin dioxide (SnO₂) in contaminated atmospheres incorporating carbon monoxide, hydrogen and methane.