The Pruitt-Baggett adduct (PBA) (MW = 438 gmol~3) which formed from the reacticn of FeCls with propylene oxide (PO) was hydrolysed in diethylether (ether) solution at different r = H2O/Fe mol ratios. The hydrolysates (PBH/r) which were insoluble in ether could be con- verted into catalytically active form (PBC/r) by a thermal treatment (baking). PBC/r (r < 1) was soluble in ether and in PO. PBC /r polymerized PO into a mixture of cyrstalline polymer and non-crystallizable oily polymer. It was found that the catalytic activity of PBC/r coıdd be varied by changing the hydrolysis conditions and the baking time.