The majority of reactions that are of chemical or biological interest occur in solution. A proper understanding of ion-solvent interactions would form the basis of quantitatively explaining the influence of the solvent and the extent of interactions of ions in solvents, thus paving the way for the real understanding of the different phenomena associated with solution chemistry. There has been an increasing interest in the behaviors of electrolytes in non-aqueous and aqueous-organic solvents with a view to investigate ion-ion and ion-solvent interactions under varied conditions. The purpose of this book is therefore, to reveal different thermodynamic and transport properties of electrolytes in non-aqueous and aqueous-organic mixed solvent media. Besides presenting simple facts and concepts, the book also presents the complex nature of ion-solvent interactions. This book intended to provide an appreciation to all those interested in chemical sciences and should be especially useful to the researchers of solution chemistry.