The pressure dependence of the CO2/propylene oxide copolymerization catalyzed by zinc glutarate was studied in this article. The effects of pressure on the product composition, yield, backbone structure of poly(propylene carbonate) (PPC), molecular weight and its distribution, and thermal stability were systematically investigated. Low pressure favored formation of byproducts (cyclic carbonate and polyether), whereas PPC still covered the majority of the product under 0.5 MPa. The copolymerization rate increased with pressure increasing under low pressures. Higher pressure led to a decline in the polymer yield because of catalyst/epoxide dilution. On the other hand, the carbonate linkage fraction decreased slightly with the drop of pressure, from 99% at 5.2 MPa to 96% at 0.5 MPa. All the PPCs synthesized under different pressures exhibited high molecular weights and broad distributions. However, the polymer prepared under 0.5 MPa possessed a relatively lower thermal stability than others. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 366-371, 2010