The Na+ capacity of cryptomelane type-hydrous manganese dioxide in aqueous, methanolic and propan-1-olic solutions was determined using two different methods. The Na+ capacity decreases reprogressively with alcohol. This pointed to an imbibition of alcohols by the solid. Self-diffusion coefficients ((D) over bar) of sodium ions in manganese dioxide have been determined in aqueous and alcoholic (methanolic and propan-1-olic) solutions by using Paterson’s approximation equation. These coefficients (D) generally increase with alcohol concentration. The effect of alcohol addition on ion-solvent interactions is counteracted by the effect of ion-ion interactions in the exchanger, leading to an increase of ((D) over bar). Also, adding NaCl to the external aqueous or alcoholic hydroxide solution enhances Na+ diffusivity due to a weaker interaction with Cl- colons inside the oxide pores, or it may be that the addition of NaCl decreases the imbibition of alcohol by the oxide.