We synthesized MoS2 and GO composites through a facile solution process to fabricate transparent and flexible gas sensor devices. The composites were coated by spin coater on SiO2/Si substrate, and after coating, the thin film was annealed at 600 ° C for reduction from GO to rGO. Finally, the completed MoS2/rGO thin film was patterned by soft lithographic patterning process and transferred to a transparent and flexible PET substrate. To fabricate a gas sensor, Au/Cr electrodes were deposited at the edges of the patterned MoS2/rGO channel, and the gas sensor characteristics were analyzed using scanning electron microscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), UV/Visible and gas sensing system. As a results, the patterned MoS2/rGO gas sensor was very thin with a thickness of 10 nm or less, and the transmittance was confirmed to be 93%. In addition, the characteristics of NO2 gas were confirmed by varying the concentration of NO2 gas from 0.15 ppm to 5 ppm. The sensing sensitivity of the MoS2/rGO composite channel was improved about four times as compared to that of the rGO single channel. In this presentation, we will discuss potential applications of MoS2/rGO composites.