Several non-conventional electrolytes, molten salts, liquefied gas and supercritical fluids, are reviewed to show their usefulness and their possibilities in electrochemical applications. Special attention is paid to chemical and material production, material tailoring and energy conversion. In this work, molten salts are divided into high (T>473 K) and room (273 K≤T≤473 K) temperature salts. Characters and properties of representative molten salts are described for the corresponding temperature range. Some selected topics, mainly using molten halides, e.g. production of SiH4 gas, formation of metal nitrides, thermally regenerative fuel cells and thermogalvanic cells, are presented in the high temperature section. In the room temperature part, applications based on chloroaluminate melts such as AlCl3–EMIC melts are described, including electrodeposition of Al and Al alloys, Li batteries and capacitors. Finally, liquefied gas systems, such as NH3 and HCl, and supercritical fluids like supercritical water and CO2 are briefly mentioned as examples of new class non-conventional electrolytes.