The invention relates to high-functionality polyether polyols of the general formula ##STR00001## where each R'.sub.1 is an unsubstituted or substituted aliphatic or aromatic radical and each R'.sub.2 is an unsubstituted or substituted aliphatic or aromatic radical, H, OH, polyalkyl ether chain or halogen, each X is a polyalkyl ether chain or H, where at least one X is a polyalkyl ether chain, and m is an integer from 0 to 20, where Xm is H when m is 0, and n is an integer from 4 to 12, to processes for preparing such high-functionality polyether polyols and also to the use thereof for preparing polyurethanes and nonionic surfactants.