With the rapid development of sensor networks in the Internet of Things (IoT) and the Industrial Internet of Things (IIoT), gas sensors that can convert information of gas compositions and concentrations into electrical signals or other signals have become an indispensable sensing technology. The emergence of gas sensors has made gas detection and analysis technology easier, faster and smarter. In recent years, numerous scientists and engineers have continuously developed new gas sensitive materi-als, device equipment and detection technologies, which made gas sensors play an increasingly important role in environmental monitoring, gas warning, hazardous chemicals detection, food quality monitoring, medical and health fields. This special issue presents novel results in gas sensors, including metal oxide hybrid materials for gas sensing, structural design of metal oxide gas-sensitive materials, non-metal oxide gas-sensitive materials, device fabrication processes, and non-resistive gas sensor technology.