Energies of the dissociation of N-H-bonds (DN-H) in 3 phenothiazines, phenoxazine, phenoselenoazine, and 9 diphenylamines (AmH) are determined. The DN-H values are calculated from kinetic data by means of intersecting parabolas. The rate constants of the following types of reaction are used in calculations: RO2· + AmiH, R· + AmiH, Ami· + PhMe2CH, and Ami· + ROOH. As a rule, the results obtained for the reactions of different types are in good agreement with each other and with the results obtained using other methods.