This special issue of the Journal of Solution Chemistry is dedicated to Professor Robert H. Wood on the occasion of his 80th birthday. It contains work presented at the 68th Calorimetry Conference in Atlantic City, New Jersey, USA, August 18–22, 2013, that is in the symposium on Aqueous Solutions, Fluid Mixtures and Polymers—A Tribute to Robert H. Wood on the Occasion of His 80th Birthday. The different scientific topics of the lectures made for an interesting and memorable symposium for all in attendance; it was highly appreciated by Professor Wood, though unexpected health problems unfortunately precluded his participation. Because of Bob Wood’s prominent role in solution chemistry, a Festschrift in the Journal of Solution Chemistry is most appropriate, and I was greatly pleased by the enthusiastic acceptance of my suggestions concerning Symposium and Festschrift by Professor Jean-Pierre E. Grolier (Universite Blaise Pascal, Clermont-Ferrand, France), Symposium Co-Organizer, by Professor David P. Remeta (Rutgers University, New Brunswick, NJ, USA), Program Chair for CALCON 2013, and by the Editors-in-Chief of the Journal of Solution Chemistry, Professor Joseph A. Rard and Professor W. Earle Waghorne. Bob Wood’s interest in the physical chemistry of solutions now spans about five decades and is documented by his more than 150 published technical papers, the majority of which is devoted to the physical chemistry of aqueous solutions of electrolytes and nonelectrolytes. When the focus is on water as solvent, one has to realize that water is not only the most abundant substance on the surface of the earth, it is also the only substance on earth occurring naturally in all three states of matter. Water is important for the structure, the stability and the function of biomolecules, that is to say, it has a controlling influence on biochemical processes and is thus a prerequisite for the emergence of life as we know it. Professor Wood’s scientific work may be subdivided roughly into six topics listed below. For each topic I have included one or more representative publications: