<p>Molybdenum disulfide (MoS₂) nanostructures have attracted significant interest for gas sensing applications due to their layered structure and surface activity. In this work, MoS₂ nanoparticles and nanoflowers were synthesized through a controlled hydrothermal process, and their morphology-dependent oxygen sensing performance was systematically investigated. By adjusting the reaction conditions and the use of a morphology-directing agent, two distinct MoS₂ nanostructures were obtained and confirmed through X-ray diffraction and scanning electron microscopy analyses. Gas sensor devices were fabricated by depositing the synthesized MoS₂ materials onto silicon substrates using a dip-coating technique, followed by thermal treatment and electrode formation. The sensing behaviour was evaluated by measuring resistance variations under oxygen exposure at room temperature. The results show a distinct and repeatable electrical response to oxygen gas, demonstrating the feasibility of MoS₂ as an active sensing material. A comparative analysis reveals that nanoflower-shaped MoS₂ exhibits enhanced sensing response compared to nanoparticles, which is attributed to its higher surface area and improved gas–material interaction. This study highlights the importance of nanostructure morphology in tuning the sensing performance of MoS₂-based sensors and demonstrates a simple, low-cost approach for developing efficient oxygen gas sensing devices.</p>