This book contains some of the papers presented at the ACS meeting symposium Ionic Liquids: Science and Applications, held at the 243rd National ACS meeting in San Diego, California, March 25-29, 2012. The symposium contained nine sessions (Energetic Ionic Liquids; Physical Properties/Physical Chemistry; Ionic Liquids for Fuel, Energy, and Chemical Production; Biomass and Renewables; Advanced Electrolytes; Molecular Modeling; Nanomaterials; New Materials; and Biotechnology). More than 75 presentations were given. The overarching theme of this symposium was the science and applications of ionic liquids. No longer are ionic liquids interesting simply because they could be considered part of the next generation of "green" solvents, but their unique physical and chemical properties make them a wholly unique class of solvents. As shown in the presentations, the fundamental science gleaned from physical chemistry, molecular modeling, and characterization of ionic liquids facilitatesthe proliferation of ionic liquid applications in biotechnology, advanced electrolytes, and nanomaterials, to name but a few areas where ionic liquids are being investigated.