The relevance. The most common fire extinguishing composition for the localization and elimination of natural and man-made fires is water. Almost annual increase in the areas of fires in the boreal zone, as well as the remoteness of fires from water sources, necessitates an increase in the resource efficiency of extinguishing. The main task in extinguishing man-made fires is to reduce the consumption of fire extinguishing agents, which will reduce the risk of excessive water flooding of the premises and material costs for the restoration of facilities. For these purposes, it is advisable to improve existing and develop new fire extinguishing compositions. The insufficient knowledge of the processes occurring during the interaction of drops of various typical fire extinguishing liquids with the surface of combustible materials, and the high scientific and practical significance of such studies determines the relevance. Purpose: to establish the patterns of wetting, spreading and evaporation of drops of fire extinguishing compositions on the surfaces of combustible materials during conductive heating. Object: fire extinguishing compositions (water; flame retardant solutions, FR-Les, bischofite; bentonite suspensions; foam concentrate emulsions) of various concentrations. Methods. The study of wetting and evaporation of drops of fire extinguishing compositions was carried out by the method of a «fixed» drop (placed on a solid surface using an electronic dispenser). To determine the geometric characteristics of the drops, a shadow optical system was used, and the obtained images were processed using special software using the «tangential 1» and «Young–Laplace» methods. Results. The main patterns of wetting and evaporation of drops of fire extinguishing compositions on the surfaces of combustible materials (birch leaves, wood, laminated chipboard, linoleum and polyvinyl chloride) have been established. It is shown that in suppressing the pyrolysis of combustible materials in the depth of the layer, compositions with a lower surface tension, penetrating into deeper layers of combustible material, will be more effective. Under such conditions, fragments of materials heated to high temperatures are cooled, and generation of fuel – gaseous products of thermal decomposition – is suppressed. It was established that the dominant mechanism for suppressing combustion and pyrolysis when extinguishing combustible materials (namely, when using fire retardants, bischofite, bentonite, FR-Les) is the formation of a protective layer on the surface of elements of substances and materials, and not heat absorption during solvent evaporation. The dependences of the time-average evaporation rates of droplets of fire-extinguishing compositions on the surface heating temperature are approximated by the exponential curve W_E  = a∙T^b.