Purpose. Fire extinguishing efficiency of flooding with temperature-activated water (TAW) sprays depends on the constituent droplets size and their distribution density. This work is aimed at determining effective characteristics of TAW polydisperse droplet phase for extinguishing fires in confined spaces. The research objectives are: 1) theoretical research of TAW extinguishing capacity dependence on its discharge parameters; 2) developing a generalized model of droplet motion in highly heated fluxes based on the physical process of TAW droplets evaporation in hightemperature environment; 3) modeling the evaporation process of TAW polydisperse droplet phase using the MathLab hardwaresoftware system. Methods. Chemical thermodynamics theory has been used to study evaporation and motion processes of TAW droplet phase. Similarity theory and algorithms theory have been used to simulate the evaporation process of TAW polydisperse droplet phase. Findings. The research has made it possible to establish that the most effective fire extinguishing characteristics are exhibited by temperature-activated water sprays, having droplets with a diameter of less than 5 µm distribution density of more than 60 %. In addition, it has been found that evaporation process of TAW sprays containing a greater number of first mode droplets has a parabolic-asymptotic character. Research application field. The compiled model can be applied to describe the evaporation process of water polydisperse media in highly heated fluxes, as well as to increase flooding efficiency with TAW sprays. Conclusions. Flooding process by means of TAW simulation makes it possible to determine the most effective fire extinguishing characteristics of its discharge for flooding. In further studies, it is advisable to simulate TAW sprays with inhibiting water-soluble salts evaporation process.