Poly(propylene glycol) [alpha-hydro-omega-hydroxypoly(oxypropylene)] of number-average molar mass (M) over bar(n), = 2000 g.mol(-1) (PPG2000) was cyclised with high conversion (ca. 75%) by reaction with dichloromethane in the presence of powdered KOH. The cyclic product was separated from chain extended polymer by preparative GPC, giving an overall yield of polymer ((M) over bar(n) = 2000 g.mol(-1), narrow molar mass distribution) in excess of 50%. Characterisation by analytical GPC and C-13 NMR spectroscopy confirmed cyclisation. DEFT and H-1-coupled NMR spectra were used to show that the links in cyclic poly(oxypropylene) were 77% single acetal, 12% double acetal and 11% triple acetal (or higher). This complexity probably results from competitive reaction with water introduced with KOH.