Room-temperature ionic liquids (RTILs) constitute currently an emerging research field. Novel applications are introduced nearly monthly. Highly-efficient and green electrolyte systems, organic synthesis and separation applications, solar cells, toxic gas capture, treatment of nuclear waste are just a short list of areas, where RTILs act among the primary gears. The present book features electrochemical applications of RTILs. Those currently experience a boom due to explosive number of new portable electronic devices needing ever better power supplies. We disseminate our established methodology to investigate electrochemically relevant properties of pure RTILs and their mixtures with molecular solvents. The methodology relies on the combination of conductometry, densimetry, quantum chemistry electronic structure techniques and larger-scale empirical molecular dynamics simulations. We discuss a comprehensive set of imidazolium- and pyridinium-based RTILs to outline research priorities and future directions towards highly-efficient electrolyte systems of the future. The book reports experimental and computational results of our labs during the last five years.