Nickel(II) formate dihydrate Ni(HCOO)2.2H2O, is obtained as green crystals by evaporation of a solution of nickel carbonate in formic acid. The anhydrous salt is obtained when the dihydrate is heated to 140 °C; at 250°C, finely divided nickel metal is produced. Hence, nickel(II) formate is used in the production of nickel catalysts.