The thermodynamics of anion exchange of the systems NO3-/Cl-, NO3-/Br- and NO3-/SCN- in hydrous ceria in mixed (methanolic) solutions has been studied. NO3- is preferred by ceria to Cl- and SCN- due to the enthalpy term while the NO3-/Br- exchange is entropy directed. The addition of 30 and 60% (w/w) methanol decreases Delta G(0) and increases Delta H-0 and Delta S-0 of the exchange of Cl- for NO3- in hydrous ceria and thus the increase of selectivity constant is due to the entropy term. In the case of the exchange of Br- for NO3-, a decrease of the selectivity constant occurs at 30 and 60% (w/w) methanol which is due to entropy changes. Also, on addition of alcohol up to 60% (w/w), in the case of the exchange of SCN- for NO3- the increase of Delta G(0) and the decreases of Delta H-0 and Delta S-0 are due to entropy changes. Changes in ion solvent interactions in the aqueous phase lead to an increase in Delta H-0 and Delta S-0, and the decrease in Delta H-0 and Delta S-0 on the addition of methanol is due to the change in the solid phase interactions.