Rotational and translational diffusion of a hydrophilic spin probe tanol have been studied for the hexagonal, lamellar and isotropic phases of a lyotropic system containing water and a nonionic surfactant decyldimethylphosphine-oxide. Rotation of the probe in the aqueous region of the lyomesophases and of the micellar solutions is only to a small extent hindered in comparison with rotation of tanol in pure water. The observed high values of translational diffusion coefficient of tanol provide complementary evidence of the high mobility of water molecules in lyomesophases. The hexagonal/liquid phase transition causes only subtle changes in the ESR spectra parameters whereas changes at the lamellar/liquid phase transition are more pronounced. Transition enthalpies and changes in diffusion parameters have been compared for the phase transitions in the system studied and in phospholipid-water systems. Existence of direct specific interaction of tanol molecules with the polar head groups on the surface of micelles is suggested in order to explain the obtained values of hyperfine splitting constant and of translational diffusion coefficients.