Ionic liquids (IL) are low melting organic salts with unique properties, which make them of increasing interest for applications as solvents, reaction media and functional additives. Polymerization in ILs is one of the methods of production of ionogels—polymer membranes containing immobilized ILs which are widely investigated, e.g. as solid polymer electrolytes. Application of photochemical initiation gives special advantages—very short reaction time, ambient reaction temperature and full control of the reaction. All this means that the interest in photopolymerization in ILs is continuously increasing. Therefore, development and investigation of photoinitiators suitable for application in IL-containing systems has become especially important. This review provides basic information on ILs, photochemical reactions in ILs and of ILs, photoinitiation in ILs, and IL-containing photoinitiators.