Abstarct: In this thesis, we study the morphology, structural and gas sensing properties of molybdenum oxide laxyers deposited on glass and silicon substrates by hydrothermal, Blade and thermal evaporation methods. To characterize the samples, X-ray diffraction scanning electron microscopy (FESEM) and Raman analysis were used. The results of X-ray diffraction analysis showed α-phase were synthesized in hydrothermal sample. After performing the gas sensing tests, this sample was estimated for an ethanol gas at an optimum temperature of about 260 ° C. The lowest and highest sensitivity calculated from this sample was 21.3 % and 75% (for 100-100 ppm), respectively. The results of the X-ray diffraction analysis in X-ray diffraction patterns showed the formation of a single-phase α for the synthesized sample showed that after the FESEM, the results indicated that the Nano-scale capsules were formed in a laxyer shape, which was also confirmed by the XRD analysis. After performing the gas sensing tests, this sample was estimated for an ethanol gas at an optimum temperature of about 260 ° C. The lowest and maximum sensitivity calculated from this sample was 24% and 82%, respectively (100-1000 ppm). Finally, molybdenum oxide deposited on silicon wafer via two methods including blade and thermal evaporation, and finally, the sensitivity of the silicon samples was investigated in contract with hydrogen gas, which was the most sensitivity reported for about 2500 ppm was reported at about 85.2 %.