Sensitivity characteristics of ZnO-based semi-conductor gas sensors to ethanol vapours have been investigated with lanthanum oxide and palladium. The sensitivity of the sintered elements were promoted by the addition of La2O3 and Pd. Further, the sensor operating temperature was reduced with the noble metal. These elements have been tested for cross sensitivity for different gases and it has been confirmed that these are highly sensitive and selective for ethanol vapours at 175 degrees C in air atmosphere. The promoting effect of the sensitivity of the sensor elements with lanthanum oxide seems to be related to the selectivity to oxidation of ethanol vapours.