The characteristics of defective ZrS 2 monolayers containing S-vacancies adsorbed various gases (NO, NO 2 , CO, SO 2 , N 2 , H 2 , O 2 , CO 2 ) were studied using a theoretical approach based on the density functional theory calculations. A favorable configuration for each gas adsorption was also found. The structural properties of defected ZrS 2 monolayers with S-vacancies adsorbed the given gas contents were elucidated. The obtained results show that the defected ZrS 2 monolayers with S-vacancies enhance the capacity of the gas adsorption in respect of the perfect ZrS 2 structures. Among those gases, the CO 2 , CO and N 2 molecules are physically adsorbed on S-vacancies of the defected ZrS 2 monolayers, whilst the O 2 , NO, SO 2 molecules are chemically adsorbed in the areas closed to S-vacancies of the ZrS 2 monolayers. Moreover, a NO 2 molecule can be separated by a S-vacancy of the defected ZrS 2 monolayer. The results of this work suggest that defective ZrS 2 monolayers with S-vacancies can be used as an adsorbent using in gas sensors to detect CO 2 , CO and N 2 gas contents. Therein, the highest sensitivity in detecting N 2 molecules is observed.