The diffusion coefficients of alkanolamines in water at infinite dilution and the mutual diffusion coefficients of aqueous N,N-diethylethanolamine (DEEA), N,N-dimethylethanolamine (DNMA), monoisopropanolamine (MIPA), piperazine (PZ) and sulfolane solutions were measured using the Taylor dispersion technique. Experimental results for temperatures from 30 to 70 degrees C and at atmospheric pressure as functions of the concentration of alkanolamines from 10.5 to 4 (or 2)} kmol. m(-3) are reported. The densities and viscosities of the aqueous solutions were also measured. The diffusion coefficients of solutes in water at infinite dilution were found to depend on the characteristics of the solutions, such as the sizes of the solutes and the intermolecular interactions between the solutes and water. The mutual diffusion coefficients were correlated through an Arrhenius-type equation and also through the UNIDIF equation. The UNIDIF model was found to yield better representations of the data than the Arrhenius-type equation. The mutual diffusivity data were also represented by a free-volume expression. The average collision diameters of the pair-molecules as a function of concentration and temperature were calculated. The relationships between the hard sphere diameter and the van der Waals diameter of solutes are discussed. The results of this study can be used for developing a kinetic model for gas absorption using aqueous alkanolamine solutions as absorbents.