An early detection and rapid transmission of the message about a fire plays an important role in reducing the severity of the consequences from fires, which ensures the timely adoption of measures for its liquidation. Thus, the purpose of this article is to review issues of applying thin-film resistance thermometers as the primary high-speed detectors in fire alarm systems. This opens up great opportunities for the development of multiband systems based on microelectronics technology. Thin film thermosensors on a massive substrate combine the functions of a threshold sensor as well as a measuring transmitter operating in the thermal finder mode. As a threshold sensor, the thin-film termosensor is, in fact, a time sensor (signal sensor) when the abrupt change in the temperature of the control surface or the heat flow is used as the alarm information. As the thermal finder of fast processes, film thermosensors allow, in addition to detection of existence of “emergency” situations (fire-flash, the combustion front, shock wave, detonation, the beginning of explosive reaction of gas mixture, etc.), to monitor process conditions, to determine the degree of risk and the dynamics of the anomalous process, to monitor the thermal state of technical objects and the environment. The results of the conducted field tests using a specially designed optical stand allowed us to make an unambiguous conclusion about that film thermosensors, with a time response less than one microsecond, can perform the function of a very early detection of fire or explosion on various potentially dangerous objects. Thus, the use of film thermosensors in radio systems for early detection of fire and other emergencies, will allow radically change the existing situation for the protection of people and objects from fire and accidents.