Polyether polyols can be prepared by reacting polyols with epoxides in the presence of basic catalysts, by treating the polyether polyols containing the basic catalysts with OH-functional solid compounds of metals of groups III to VIII of the periodic system of the elements (Mendeleyev), the compounds being insoluble in the polyether polyols and having BET surface areas of from 10 to 1000 m2/g, isolating the solid inorganic compounds laden with the basic catalysts from the polyether polyol and using them in the reaction of polyols with epoxides, or bringing the isolated inorganic compounds laden with the basic catalysts into contact with the polyols that are to be used in the reaction with epoxides, separating those polyols from the inorganic compounds and delivering them to the reaction with epoxides.