The 2,2,6,6-tetramethyl-I-piperidinyloxy free radical (TEMPO) was used as a probe to study the changes in hydrogen bonding between the phenolic OH group and the ON group of the radical by means of NMR and EPR.13C NMR contact shifts induced by TEMPO were measured for five phenols. Formation of intermolecular hydrogen bond between a phenol and TEMPO molecule causes noticeable increase of14N hyperfme coupling constant in the radical and appearance of negative spin density on carbon nuclei of C-OH fragment in the phenol.