A procedure was developed for the synthesis of the kinetically stable nitroxide 2-(N-tert-butyl-N-hydroxyamino)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl containing the sterically hindered hydroxylamino group. The crystal and molecular structure of this compound was determined. The isolation of this nitroxide hydroxylamine in the individual state enabled a new procedure for the preparation of its oxidation product, viz., the corresponding nitroxide biradical. The results of quantum chemical calculations of the electron exchange in the biradical molecule are in good agreement with the experimental data on the triplet ground state of the molecule in the crystal obtained earlier.