This work focused on the anionic polymerization of octamethylcyclotetrasiloxane (D4, D = Me2SiO2/2) initiated by a new kind of initiator hexamethyldisilazyl-lithium (MMPi). 29Si-NMR spectroscopy and gas chromatography (GC) were used to characterize the polymerization products. The process was accelerated by adding a small amount of high activity monomer D3 and by raising the polymerization temperature. At the end of polymerization more than 95% of the monomer was converted to polymer and only a very small amount ofD4 and D5 remained in the polymers.