In this paper, the SnO₂–Al₂O₃ binary thin-film system has been deposited on a glass substrate by the spray pyrolysis technique. The effect of aluminum concentration on the structural, electrical, thermoelectrical, optical and photoconductivity properties of films was studied. The [Al]/[Sn] atomic ratio was in the range 0–100 at.% in solution. X-ray diffraction analysis shows that all films with different doping levels have polycrystalline SnO₂ cassiterite phase. At doping levels of 40 at.% and above, the Al₂O₃ phase was observed and the sheet resistance of the films increased with increasing Al doping in the ranges from 5 at.% to less than 40 at.% and more than 60 at.% due to the substitution of Al³⁺ with Sn⁴⁺. Minimum sheet resistance of films was found in the range 40–60 at.%. Using Hall effect measurements, the majority carriers concentration obtained was of the order of 10¹⁸ cm⁻³. Hall effect and thermoelectrical measurements show that at doping levels between 10 and 20% and also higher than 60 at.%, majority carriers change from electrons (n-type conduction) to holes (p-type conduction). Also, a higher Seebeck coefficient value equal to-341 μV K⁻¹ was obtained for the 30 at.% Al-doping level. The average transmittance of the films at low doping levels was about 75–90%. The photoconductivity properties of SnO₂–Al₂O₃ thin films increased with increasing doping level.