Densities and refractive indices of binary mixtures containing sulfolane (2) ? alkanediols (1) (1,2- ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol and 1,4-butanediol) were measured across the whole composition range and in the temperature between 298.15 and 313.15 K. From the experimental measured data, excess molar volume VEm , partial molar volume Vm;i, apparent molar volume V;;i, and excess coefficient of thermal expansion aEp were calculated. The computed quantities of excess molar volume have been fitted to the Redlich–Kister equation to derive the coefficients and to estimate the standard error values. Also, the experimental refractive index data were applied to the Reis equation allowing excess refractive index nE D to be calculated and then fitted to the Redlich–Kister equation. The excess refractive indices were found to be negative for the all temperatures. The thermodynamic properties have been discussed in terms of the nature of molecular interactions between the components in the binary mixtures.
