Activated monomer cationic ring-opening polymerization of ethylene oxide initiated with 1H,1H,2H, 21-l-perfluorooctan-l-ol, using acid exchanged montmorillonite clay called Maghnite-H+ (Mag-H+) as an effective catalyst, was carried out to obtain the corresponding homo-polymers with narrow polydispersity ratios. The molecular weights of the obtained polymers could be controlled with the feed ratio of the monomer and initiator. The effect of amount of catalyst and time on the polymerization yield and viscosity of the polymers were studied. The structure was confirmed by H-1-NMR and MALDI-TOF-MS. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 3445-3452,2010