Cyclic poly(dimethylsiloxane) (PDMS) was prepared from commercially available linear alpha,omega-dihydroxy-PDMS by a platinum-catalyzed dehydrocoupling of its chain ends with alpha,omega-dihydrido-PDMS in dilute solution. Ring closing was verified by MALDI-ToF mass spectrometry along with GPC, IR, H-1 and Si-29 NMR spectroscopy. Purification of the cyclic PDMS was achieved by inclusion complexation of linear byproducts with gamma-cyclodextrin. Cyclic yields are >= 50% and the average molecular weight (M) closely reflects that of the linear starting material. Yields of large cycles, [(CH3)(2)SiO](x) where x>6, are greater than those achieved by the traditional ring-chain equilibration route beginning with [(CH3)(2)SiO](4) and [(CH3)(2)SiO](5) [1], and the M is greater than that obtained for the cyclic product obtained from base-catalyzed cyclodepolymerization of the same alpha,omega-dihydroxy-PDMS precursor [2]. (C) 2010 Elsevier Ltd. All rights reserved.