In the food and agricultural industry, sensors are being used for process control, monitoring quality, and assessing safety. There is a growing demand for carbon dioxide (CO 2 ) sensors in the bulk food storage sector, because CO 2 sensors can be used to detect incipient spoilage and to assess CO 2 levels in modified-atmosphere packages and storage structures. The market potential for reliable and inexpensive CO 2 sensors is huge because of a wide range of applications in the agri-food industry. This review synthesizes information about the types of CO 2 sensors, analyzes their detection processes, provides a broad overview of the innovative research on the development of sensors, sensing mechanisms, and their characteristics, and outlines future possibilities for use of CO 2 sensors.