Аннотация:Wildfire has impacts on soil and soil organic matter that can differ according to the temperature reached during fire. Soil organic radicals, which usually provide protective activity of soil, degrade and lose its reactivity during overheating. The aim of this study was to elucidate the influence of overheating of soil on its protective properties to interact with organic chemical contaminants. A new technique of spin labeling and probing was applied to overheated soils. This approach was developed to characterize the protective activity of soil to reduce the concentration of contaminants in soil. Stable nitroxide radicals Tempo and 4-Amino Tempo were used as spin labels and also, they modeled contaminants. The ESR analysis showed that interaction of some soils overheated at 105 Grad C with both spin labels was accompanied by a sharp increase in soil organic radicals, and a part of spin labels were adsorbed by overheated soils. Soils overheated at 200 Grad C contained still abundant organic radicals. Their ESR signals became similar, they reduced nitroxides in a similar way but adsorption of Tempo and 4-Amino Tempo by soil constituents didn’t occur. Soils overheated at 400 Grad C mostly lost their protective properties.