We used density functional theory (DFT) in terms of energetic and electronic properties to evaluate the ability of Terthiophene (as a simplest model of polythiophene, denoted as TTP) toward detection of some atmospheric gases. By using ωB97XD /6-31G(d,p) level of theory, the sensitivity of TTP among CO, CO2, SO2, and CH3OH gas molecules has been investigated. To further understanding the electronic properties of interacted TTP, the NBO as well as density of states (DOSs) analyses were calculated for the isolated and interacted TTP with regarding to any of above-mentioned gas species. The types of interactions between these species with TTP were studied with understanding the HOMO and LUMO energies. UV-vis spectra has been calculated for all interacted systems and the data shows that the λmax values were red or blue shifted depending on the kind of analyte which are proving for successfully interaction. Based on our results the interaction energies were calculated to -16.7, -14.3, -8.2 and -5.3 kJ/mole for TTP-CH3OH, TTP-SO2, TTP-CO2 and TTP-CO respectively.