The copolymerization of carbon dioxide and propylene oxide using rare-earth-metal catalyst systems was investigated in this study. It was found that the ternary rare-earth-metal coordination catalyst consisting of Y(CF3CO2)(3) (I), diethylzinc (II), and glycerine (III) was the most effective catalyst system to generate an alternating polycarbonate. The effects of the molar ratio of catalyst components, the solvent, and the operating temperature and pressure on the yield and the molecular weight of polycarbonate were systematically studied. At an appropriate combination of all variables, the yield could be as high as 4200 (g/(mol of Y))/h and the molecular weight as high as 1.0 x 10(5) in a 12 h reaction period. The carbonate content in the resulting polycarbonate was found to be 95.6%.