Oxidation and absorption of nitric oxide can be achieved by using cobalt(Ⅱ) in aqueous ammonia solution. Nitric oxide is oxidized to soluble nitric dioxide in liquid phase. The Co(NH3)2+6 produced by cobalt(Ⅱ) ions complexing with ammonia acts as the catalyst. The oxidant is the oxygen in flue gas. Oxidation and absorption of nitric oxide proceed simultaneously. A stirred vessel with a plane gas-liquid interface was used to measure the chemical absorption rates of nitric oxide into Co(NH3)2+6 solutions. The reaction of NO with Co(NH3)2+6 can be considered as instantaneous. The gas-liquid reaction becomes gas film controlling as Co(NH3)2+6 concentration exceeds 20mmol8226;L-1. Oxygen in the gas phase is favorable to the absorption of nitric oxide

but the effect is less significant at oxygen concentration above 5.2%. The NO absorption rate decreases with increasing temperature. The kinetic equation of NO absorption into Co(NH3)2+6 solutions in the presence of oxygen is presented.