“…Therefore, a growing interest in research concerning alternative catalysts, which should be active, selective and stable as well as solve problems resulting from the use of conventional acids, is of high importance [ 6 , 7 , 8 ]. On the other hand, salts of various metals, such as boron, aluminium, gallium, indium or noble metals, e.g., copper, are also successfully used in catalysis [ 9 , 10 , 11 , 12 , 13 , 14 ], especially in the form of halometallates, because they represent high Lewis acidity, which distinguishes them from other groups of salts. The subjects of this review are metal-based ionic liquid focusing on gallium(III) and indium(III) and their performance in organic chemistry.…”