A method of preparing a hydroxy-functional polyether comprising contacting (a) a hydroxy-functional polyether containing less than or equal to about 200 ppm of a Group IA or Group IIA metal ion, and (b) an acid. Preferably the contact is carried out under reaction conditions such that a salt, which is not suitable to significantly promote trimerization reactions if the hydroxy-functional polyether is reacted with an isocyanate compound, is formed. The amount of acid is sufficient to essentially neutralize residual basic catalyst without requiring additional solids removal steps prior to use of the hydroxy-functional polyether in various applications, such as production of polyurethanes and related products, in which enhanced trimerization may not be desirable. Additional acid may also be added to convert propenyl ether units present in the polyether's backbone to propionaldehyde and the corresponding diol.