An improved method for synthesizing a double metal cyanide (DMC) catalyst
includes combining a non-aqueous solution of a first metal salt, such as
ZnBr.sub.2, with a non-aqueous solution of a second metal salt, such as
CoBr.sub.2, and with a non-aqueous solution of an alkali metal cyanide,
such as NaCN, in a single step to synthesize the DMC catalyst, Zn.sub.3
[Co(CN).sub.6 ].sub.2.
