The thermodynamic properties of maltodextrins in aqueous solutions were studied by the isopiestic method, laser-light scattering and calorimetry. Three different maltodextrin samples with molar masses between 1000 and 3000 were investigated. The second and third osmotic virial coefficients of oligomers were determined. It was found that an influence of the molar mass on the second and third osmotic virial coefficients has to be considered only for the low molecular oligomers (up to maltotriose), whereas it can be neglected for oligomers with higher molecular mass. Furthermore, the Virial Equation with Relative Surface Fractions (VERS) model was used to correlate the experimental data for the activity of water and the heat of dilution. The results of that investigation were used to predict the activity of water and some other thermodynamic properties of some other low molecular saccharides for which experimental results are available in the literature. (C) 2005 Elsevier Ltd. All rights reserved.593289303