The environmentally friendly Mn 2 (CO) 10 -based visible light photoinitiating system is a powerful method for the preparation of linear and crosslinked polymeric structures. From a practical point of view, the most important feature of this initiating system is its optical characteristics in the visible range with high quantum yield and good solubility properties. This photoinitiating system is applicable for a variety of monomers that can be polymerized via either radical or cationic mechanisms. Various complex macromolecular structures such as telechelic polymers, block and graft copolymers, polymer networks and surface modifications can be simply prepared by using halogenated precursors. This photoinitiating system is also combined with controlled radical polymerization techniques providing a mild and efficient method for polymer synthesis.