The present invention relates to a process for the preparation of a double metal cyanide (DMC) catalyst, which process comprises: (a) combining an aqueous solution of a metal salt with an aqueous solution of a metal cyanide salt and reacting these solutions; and (b) recovering the DMC catalyst from the reaction mixture, in which process the DMC catalyst is prepared in the presence of from 0.03 to0.4 mole of alkaline metal compound, based on amount of metal salt. Further, the present invention relates to DMC catalyst obtainable by such process, to DMC catalyst prepared from a metal salt and ametal cyanide salt in which the molar ratio of metal derived from the metal salt to metal derived from the metal cyanide salt is at least 2.25 and to a process for polymerization of alkylene oxides which process comprises reacting initiator with alkylene oxide in the presence of at most 15 ppm of DMC catalyst.