The microstructure of tin dioxide thin films have a great influence on the electrical performances of SnO₂ gas sensors. An O.M.C.V.d. technic is used to prepare materials with suitable textures by changing the deposition parameters. A detailed characterization of the films is presented including X-ray, S.E.M. and ESCA measurements. Special attention is given to the thickness and the grain size determinations. The influence of annealing on the textural and electrical properties is also investigated. Electrical measurements show the conductivity dependency under pure air with the tickness and the deposition temperature. A part of the results are explained by taking into account the variations of the texture (thickness, grain packing) and the stoichiometry of the films.