Densities and viscosities of arginine in (glucose + water), (sucrose + water) and (L-ascorbic acid + water) mixed solvents have been measured at T = 298.15 K by an oscillating-tube densimeter and viscometer. Standard-state partial molar volume, hydration number and viscosity B-coefficients of arginine have been calculated. The transfer volumes from water to (sugar + water) or (L-ascorbic acid + water) mixed solvents have been obtained and discussed in terms of the structural hydration interaction model. The results indicate that the partial molar volumes of transfer and viscosity B-coefficients of arginine increase with increasing the mass concentration of sugar or L-ascorbic acid, and the hydration number of arginine decreases owing to the interaction of sugar or L-ascorbic acid and the zwitterionic groups. It is concluded that the magnitude of the enhancement effect on volume and hydration number is related to the number of OH groups and the structure of mixture solvent. (C) 2004 Published by Elsevier Ltd.