A method is provided for synthesizing metal cyanometallate (MCM). The method provides a solution of AXM1Y(CN)Z; where “A” is selected from a first group of metals and M1 is selected from a second group of metals. The method adds a material including M2 to the solution to form a liquid phase material that may be either a suspension or a solution. M2 is selected from the second group of metals. The method adds acid to the liquid phase material. The addition of acid to the liquid phase material decomposes the M2 material into M2-ions. Simultaneous with the addition of the acid, a precipitate of ANM1PM2Q(CN)R.FH2O is formed, where N is in a range of 1 to 2. A variation of the above-described synthesis method is also provided.