The ClCuOCO and BrCuOCO molecules have been observed by cocondensation of the species generated from 1064 nm laser ablation of CuCl2 and CuBr2 targets with CO2/Ar mixtures. With the aid of density functional calculations and isotopic substituted experiments, infrared absorptions at 2383.9 and 2381.4 cm(-1) are assigned to the antisymmetric CO2 stretching vibrations of the ClCuOCO and BrCuOCO molecules in solid argon, respectively, Theoretical calculations predicted these molecules to be linear with a (1)Sigma (+) ground state. The interaction between CuX and CO2 is mainly electrostatic and thus induces a blue shift of the CO2 antisymmetric stretching vibration. The binding energies for ClCuOCO and BrCuOCO with respect to those for CuX and CO2 were calculated to be 12.5 and 11.4 kcal/mol, respectively. Similar experiments with AgCl and AgBr gave the analogous ClAgOCO and BrAgOCO. The binding energies were estimated to be 6.5 and 5.9 kcal/mol for ClAgOCO and BrAgOCO, respectively.