It also can be made by reacting nickel with water at 1000 C. The simplest way to make it is to heat nickel ( II ) hydroxide , nickel ( II ) carbonate , or nickel ( II ) nitrate . In some commercial processes , green nickel oxide is made by heating a mixture of nickel powder and water at 1000 Â C , the rate for this reaction can be increased by the addition of NiO . The simplest and most successful method of preparation is through pyrolysis of a nickel ( II ) compounds such as the hydroxide , nitrate , and carbonate , which yield a light green powder .