Abstract: Nickel oxide powders were perpared by high-temperature calcination.The precursor was perpared using solid state reaction method with citric acid and nickel nitrate as raw materials through changing the ratio of reactants and the addition order of reactants.The precursor and synthetic products were characterized by TG,XRD and SEM.The results show that the precursor was obtained by grinding during which the substance ratio of citric acid to nickel nitrate was 1.2∶1 and citric acid was gradually added.Then the precursor was calcined at 400 ℃ for 2 h to get the nickel oxide.No simple substance but NiO phase was found in the products,nickel oxide formed a large net structure.