Abstract Electric conductivities of the sodium salts of mono-, di-, and tri-chloroacetic acids were measured in water at 15, 25, and 35 °C. The molar conductivities were analyzed by the Fuoss-Onsager equation to obtain the limiting mobility. On the basis of the temperature dependence of the limiting mobilities, the dynamic structure of Water around these anions was investigated by means of Samoilov’s theory, Chloroacetate ions are structure maker and the degree of the positive hydration is in the order TCA−>acetate ion>DCA−>MCA−. From the results, it is shown that a competition between the different orientation of water molecules in the surroundings of –CH2Cl and –CHCl2 groups occurs, and consequently, shown that the water molecules around DCA− and MCA− ions more mobile than those around TCA− and acetate ions.