Polyols are conditioned and stabilized by mixing them at 0 to 150.degree. C. with from about 0.0001 to about 1% by weight, based on the quantity of polyol, of a silylated acid corresponding to the formula:X--[Si(CH.sub.3).sub.3 ].sub.nin whichX represents a neutral acid residue obtained by removal of the acidic hydrogen atoms from an n-basic acid having a maximum pKa value of 3, provided that the n-basic acid is not a hydrohalic acid andn represents an integer of from 1 to 3.The resultant polyol is characterized by good color and activity properties. The stabilized polyols are particularly useful in the production of polyurethanes, particularly polyurethane foams.