A process for preparing polyether polyols includes a precipitation step, a recrystallization step, and a reaction step. In the precipitation step, a multimetal cyanide compound is precipitated by reaction of a metal salt with a cyanometalate compound. In the recrystallization step, the multimetal cyanide compound precipitated above is recrystallized by adding further metal salt and/or further cyanometalate compound. The recrystallization forms a multimetal cyanide catalyst compound. In the reaction step, an initiator and one or more alkylene oxide are reacted in the presence of the multimetal cyanide catalyst compound.