Methods are presented for synthesizing metal cyanometallate (MCM). A first method provides a first solution of AXM2Y(CN)Z, to which a second solution including M1 is dropwise added. As a result, a precipitate is formed of ANM1PM2Q (CN)R.FH2O, where N is in the range of 1 to 4. A second method for synthesizing MCM provides a first solution of M2C(CN)B, which is dropwise added to a second solution including M1. As a result, a precipitate is formed of M1[M2S(CN)G]1/T.DH2O, where S/T is greater than or equal to 0.8. Low vacancy MCM materials are also presented.