Research for new and inexpensive energy storage technologies has been increasing in recent years due to the need to store power from intermittent sources such as wind and solar power. Among these advanced energy storage technologies, the Li-O2 battery is described as a suitable candidate because of its high theoretical energy density. Research has been focused on the development of suitable electrodes and electrolytes to allow high energy density and high cyclability, being the latter one of the main challenges. Poor cyclability is often related to undesirable reactions, and one of the sources of this problem is the presence of water in the electrolyte. Nevertheless, it has been shown that trace amounts of water can also catalyze desirable reaction steps in the operation of a Li-O2 battery. Therefore, careful control of water content in the electrolyte of Li-O2 batteries becomes an important task. In this context, this work presents the equilibrium study of water adsorption from dimethyl sulfoxide, a solvent commonly considered for electrolytes of Li-O2 batteries, using 3A zeolites as the adsorbate. Batch adsorption experiments with different concentrations of water and mass of adsorbate were combined to determine the water removal capacity at different conditions of temperature (20 °C, 35 °C, and 50 °C). Adsorption data were fitted to adsorption models (Langmuir, Freundlich, and Dubinin-Radushkevich) to obtain their constants. Additionally, the regeneration of zeolites was evaluated. These data have the potential to be used by other researchers in the development of Li-O2 batteries with electrolytes with precisely controlled water content.