Water activities of binary and ternary mixtures containing polyols were mea
sured using an electronic hygrometer with temperature ranging from (10 to 3
5) degrees C. The concentrations of the mixtures varied according to the so
lubility limit for each polyol (D-sorbitol, D-mannitol, xylitol, meso-eryth
ritol, and glycerol). Results were compared with the group contribution-bas
ed models ASOG and UNIFAC. The predictions using parameters from the litera
ture were poor, probably as a consequence of the strongly polar hydroxyl gr
oups bounded to consecutive carbon atoms in the polyol molecule. Better agr
eement was obtained by readjusting some of the interaction parameters. The
data bank used in this procedure included water activity data as well as po
lyol solubility data taken from the literature. The best results were achie
ved using the UNIFAC-Larsen model with an average relative deviation of 0.9
% for water activity and solubility data.