Binary mutual diffusion coefficients (interdiffusion coeffcients) have been measured for aqueous solutions of beta-cyclodextrin (beta-CD) at concentrations from (0.002 to 0.008) mol center dot dm(-3). The effect of temperature, from (298.15 to 312.15) K, was also analyzed. The concentration dependence of D is discussed on the basis of Hartley's equation. The activation energy for the diffusion process, 18719 J center dot mol(-1), was calculated from data of D at different temperatures. This activation energy is in good agreement with that estimated using Stokes-Einstein equation (18644 J center dot mol(-1)). Activity coefficients for aqueous beta-CD solutions were also estimated from Hartley equation and experimental D.