The interaction of small molecules with low-dimensional structures plays a major role in many important practical processes such as metal hydride formation, energy storage systems, and catalysis. In this work, we carried out first-principles density functional theory calculations of hydrogen and oxygen adsorption as well as their diffusion on subnanometer MoS nanowires. The nanowires are robust against adsorption of hydrogen. On the other hand, interaction with oxygen shows that the nanowires can oxidize with a small barrier (0.20 eV). In addition, our findings indicate that the interaction with hydrogen or oxygen does not modify the metallic character of the nanowire. The calculations also show that the singlet state is the most stable for 2O adsorbed on the MoS nanowire. Such results open the path for understanding the behavior of MoS nanowires under a realistic environment.