An effective one-pot polyrotaxane synthesis with control of the threading ratio is realized. 2,5-Bis(chloromethyl)-4-methoxy-1-octoxybenzene (PMOC) is condensed with a starting rotaxane consisting of a bisphenol A salt threaded into beta-cyclodextrin (beta CD), to lead to a beta CD-threaded polyether. We demonstrate that the threading ratio of beta CD on the polyether chain (ratio between the polymer repeat units and the beta CD in polyrotaxane) can be varied from zero to unity depending on two parameters: the reactant concentration and the bulkiness of the counter-ion stopper in the starting rotaxane. (C) 2007 Elsevier Ltd. All rights reserved.