Activity coefficients and volumetric properties for the NaBr + maltose + water system were determined at 298.15 K by cell potential and density measurements, respectively. The activity coefficients were evaluated respectively from the cell potential data using the Debye-Huckel and the Pitzer equations, and they are in quite agreement with each other. Infinite-dilution apparent molar volumes for maltose (V-Phi(0),(S)) in aqueous NaBr and those for NaBr (V-Phi,E(0)) in aqueous maltose were evaluated, respectively. Free energy and volumetric interaction parameters (g(ES) and v(ES)) were also obtained. These results were discussed in terms of the stereochemistry of saccharide molecules and the group additivity model.