The present invention is directed to a process for preparing a double metal cyanide catalyst of Formula I (Ma[M′(CN)cZw]b.zA), wherein M is a main group or transition metal cation, M′ is a main group or transition metal cation, which can be the same or different from M, Z is an anion or ligand other than cyanide, A is an amphiphilic agent selected from heteroatom-containing organic compounds having at least one polar head group and an aliphatic, aromatic or partially aromatic moiety having a number of 6 to 42 carbon atoms, w is an integer greater than or equal to 0, but lower than c; a, b and c are integers greater than or equal to 1 so that catalyst (I) is electrically neutral, and z is a number from 0 to 12, which process comprises (a) reacting a metal salt of Formula II (MeXf), wherein X is an anion and e and f are integers greater than or equal to 1 so that metal salt (II) is electrically neutral, with a cyanometallate complex of Formula III (Dg[M′(CN)c]b), wherein D is a cation and g is an integer greater than or equal to 1 so that complex (III) is electrically neutral, and M′, Z, c, w and b are defined as described above, in the presence of the amphiphilic agent A and optionally a solvent L to obtain a double metal cyanide adduct of Formula IV (Ma[M′(CN)c]b.xA.yL), wherein x is a number greater than or equal to 1 and y is a number greater than or equal to 0; and (b) thermally treating the adduct (IV) to obtain the double metal cyanide catalyst of Formula (I).