Biophysical Chemistry: Molecules to Membranes is a one-semester textbook for graduate and senior undergraduate students. Developed over several years of teaching, the approach differs from that of other texts by emphasizing thermodynamics of aqueous solutions, by rigorously treating electrostatics and irreversible phenomena, and by applying these principles to topics of biochemistry and biophysics. The main sections are: (1) Basic principles of equilibrium thermodynamics. (2) Structure and behavior of solutions of ions and molecules. The discussions range from properties of bulk water to the solvent structure of solutions of small molecules and macromolecules. (3) Physical principles are extended for the non-homogenous and non-equilibrium nature of biological processes. Areas included are lipid/water systems, transport phenomena, membranes, and bio-electrochemistry. This new textbook will provide an essential foundation for research in cellular physiology, biochemistry, membranebiology, as well as the derived areas bioengineering, pharmacology, nephrology, and many others.