Abstract: The reaction between COS and O(3P) had been studied by means of the density functional theory (DFT) and G3B3 methods. The geometries for the transition states,intermediates, reactants and the products had been completely optimized at B3LYP/6-31G~*, B3LYP/6-311~(++)G~(**) and G3B3 computational levels.The transition states and reaction mechanism had been confirmed by the vibrational analysis and the internals reaction coordinate (IRC) calculations.The results obtained indicate that the main products of COS r...