[Co(NH3)4Cl2]Cl + 3NaOH + 3H2O → CoO(OH) + 4(NH3•H2O) + 3NaCl
Dichloridotetraamminecobalt(III) chloride react with sodium hydroxide and water to produce metacobalt(III) hydroxide, ammonium hydroxide and sodium chloride. Sodium hydroxide - concentrated cold solution.