Abstarct: In this thesis, the role of hybrid nanocomposites in enhancing the performance and stability of gas sensors has been investigated. The main focus of the study is on mextal oxide/polymer and mextal oxide/two-dimensional material systems, since these structures can reduce the limitations of individual materials through synergistic effects. First, the importance of monitoring pollutant gases, toxic gases, and humidity from the perspectives of human health, industrial safety, and environmental control is explained. Then, different families of gas-sensing nanocomposites, including conducting polymers, mextal oxides, graphene-baxsed structures, rGO, MXene, and g-C3N4, are introduced and classified. Subsequently, the main mechanisms of performance enhancement, including surface adsorption, charge transfer, heterojunction formation, depletion laxyer formation, the role of oxygen vacancies, porosity, morphology, and chemical and electronic sensitization, are analyzed. The review of the literature shows that the targeted combination of organic, inorganic, and two-dimensional components can lead to an increased sensor response, reduced operating temperature, improved selectivity, and shorter response and recovery times. It was also found that the long-term stability of sensors depends on factors such as humidity, temperature, corrosion, radiation, surface contamination, and signal drift. The comparison of reported research results showed that no nanocomposite has absolute superiority in all performance indicators, and the selection of a suitable material should be baxsed on the type of target gas, operating conditions, operating temperature, stability, and practical applicability. Finally, the design of multicomponent nanocomposites with controlled interfaces, stabilization of two-dimensional materials, reduction of humidity effects, improvement of selectivity, and the use of sensor arrays and intelligent data processing are introduced as proposed pathways for developing more stable and reliable gas sensors.