We explore several fundamental questions concerning the exceptional role of hydrogen bonds in determining acid-base reactivity in chemical and biological environments. We also explore the unique acid-base properties of cationic acids RNH3+ which are very important in biological systems. In collaboration with Prof. J. T. Hynes, Department of Chemistry and Biochemistry , University of Colorado at Boulder and with Prof. Victor Batista, Department of Chemistry, Yale University (BSF, 2007-2011, Solute-solvent interactions and proton transfer reactions of physiologically protonatable groups in aqueous solutions and their biochemical significance).