The purpose of this paper is to demonstrate the possibility of modifying the sensitivity of tin dioxide (SnO₂) films by depositing metallic catalysts on the surface of SnO₂ layer. The aim is to reduce the effect of ethanol which is considered as an interfering gas in many domestic or industrial applications. Two catalysts have been so studied (platinum and palladium), deposited on two types of SnO₂ layers which present different textures. Both catalysts reduce the sensitivities to ethanol, carbon monoxide and methane. But the decrease of the alcohol sensitivity is more significant and consequently, the relative sensitivities to CO and CH₄ are increased. This effect is more important with the SnO₂ layers which have a high porosity. An other application where tin dioxide sensors can be used is the automotive application. In this case, nitrogen oxides are considered as interfering gases for the carbon monoxide detection. Several catalysts are studied in order to decrease the influence of nitrogen oxides and especially the conductance decrease under NO₂. One of the catalysts which can be used to reduce the nitrogen oxide effect is rhodium. The results obtained with such rhodium films deposited on SnO₂ sensors allow us to consider future applications in the automotive field.