Relaxation properties of D(+)-glucose and D(+)-maltose in aqueous solutions have been studied at low solute concentrations (c <= 0.3 mol/I), using ultrasonic absorption spectrometry in the frequency range 1 400 MHz. All spectra revealed excess absorption with relaxation characteristics at frequencies around 80 MHz. In conformity with previous assignments this relaxation is discussed in terms of a rotational isomerization of the exocyclic hydroxy methyl group of the carbohydrate molecules. An additional relaxation term with relaxation frequency around 13 MHz was found in the spectra of the maltose solutions. This term is related to the rotation of the glucose rings of the disaccharide relative to one another. (C) 2008 Published by Elsevier B. V.