In this study, The gas sensing properties of Al/Al2O3/p-Si structure was investigated. Al2O3 was made in by atomic layer deposition (ALD) method. The temperature dependent electrical characterization of produced sample was performed in gas atmosphere (carbon monoxide and carbon dioxide) at different temperatures (300-450 K) and different gas concentrations (50-2000 ppm). The results show that the reaction between the gas molecules and the surface of the sample is based on the charge transfer mechanism. The response and recovery times are calculated 11 and 16 s, respectively.