Abstarct: In this thesis, first pure and Mn doped- Sno2 Thin films were prepared by spray pyrolysis method. Then structural, optical and electrical properties of the laxyers were investigated. study of the X-ray diffraction spectra of the samples showed that the laxyers are poly crystalline and have a quadrilateral rutile phase. The analysis of XRD data showed that the average crystalline size is larger in the pure sample and decreases with the increase of manganese concentration. The surface morphology of the laxyers showed that they are composed of a dense packing of spherical particles. More over, the thickness of the laxyers measured from cross-section SEM images was around 400nm. Investigation of the optical properties of the laxyers showed that Mn-doped-SnO2 laxyers have still a good transparency in the wavelength range of 300 to 1100 nm. The band gap of the pure SnO2 was about 3.79 eV, which adding of 8 atomic percent of Mn it decreases to 3.60 eV. More over,The crystalline quality of the Mn doped- laxyers showed a slight decrease compare with the pure laxyers. The study of the electrical properties of the samples showed that, with increasing of Mn content, the electrical resistance of the laxyers increases, and the mobility and conductivity decrease.