Adsorption and degradation of C2N2 in cereals were investigated using a static method under controlled conditions. C2N2 residue in cereals, its adsorption, and volatilization were studied with gas chromatography. Degradation products were determined using a flow injection analyser (FIA).The results showed that cereals had a very high C2N2 adsorption capacity with a rate over 90% within 1 h fumigation. The order of adsorption capacity was paddy >sorghum >maize >barley >wheat. C2N2 in cereals could degraded into HCN. Under the aeration condition, C2N2 and HCN degraded from C2N2 were slowly volatilized from cereals. The volatilization rates of C2N2 from wheat and barley were always higher than that from maize, sorghum and paddy. Level of HCN from wheat, barley, maize and sorghum were always higher than that from paddy. The residue dynamics of C2N2 and HCN degraded from C2N2 in cereals conformed with the first-order kinetics index model after the aeration. The half lives of C2N2 in wheat, barley, maize, sorghum and paddy were 1.82, 257, 2.81, 1.97, and 2.98 d, respectively, and those of HCN were 4.46, 4.30, 4.01 and 3.94 and 5.26 d. The absorbed C2N2 could degraded into HCN, NH4+, and a small amount of NO3- and NO2- but there were differences among cereals. Four degraded products (HCN, NH4+, NO3- and NO2-) were determined in wheat and maize, and three (HCN, NH4+ and NO3-) were determined in paddy, and only two degraded products (HCN and NH4+) were determined in barley and sorghum. [ABSTRACT FROM AUTHOR]