This article presents findings of experimental research into suppressing the thermal decomposition of forest fuel (birch leaves, spruce needles, kindling wood and mixed forest fuel) under conditions of exposure water aerosol and single water droplets, as well as water with specialized additives. We used typical model of fire source with fixed height 0.04 m and varied diameter 0.02-0.1m. Water spraying process, as well as interaction between water and forest fuel was registered using high-speed video camera (recording frequency 6·105 fps) and panoramic optical methods (“Particle Image Velocimetry”, “Shadow Photography”). We established principles of water additions’ influence on termination of combustion and thermal decomposition of fire source model.