Tin dioxide SnO₂ is one of the most common materials used in the fabrication of semiconductor gas sensors The principle of such sensors is based upon the variations of conductivity induced by adsorption of various gases. A low pressure OMCVD apparatus has been developed in order to obtain tin dioxide thin films. Structural and electrical properties have been investigated by different techniques: S.E.M., X-ray diffraction and conductivity measurements in different atmospheres. A correlation is found between the deposition parameters and the electrical properties of CVD-SnO₂ thin films.