To probe the effect of ionic liquid structure on the thermophysical properties of aqueous D-xylose solutions, density and viscosity measurements were carried out at 298.15 K for ternary solutions comprising D-xylose and an ionic liquid {1-hexyl-3-methylimidazolium bromide ([HMIm]Br), 1-octyl-3-methylimidazolium bromide ([OMIm]Br), and 1-decyl-3-methylimidazoliume bromide ([DMIm]Br)} in aqueous medium. These data have been used to calculate some important thermophysical properties including standard partial molar volumes (V-phi(0)), viscosity B-coefficients (using the Jones-Dole equation), and free energy of activation per mole of solvent (Delta mu(0 not equal)(1)) and solute (Delta mu(0 not equal)(2)) from Feakin's transition state theory. It was observed that all the parameters increase with increasing both the concentration and the alkyl chain length of the imidazolium ring of the ionic liquids. These quantities have been utilized to rationalize structural interactions and the hydration behavior of D-xylose.