Gel permeation chromatography (GPC) is widely used to measure the molecular weights of linear polymers. A detailed analysis of high-quality GPC data is an important source of information about the kinetics of a polymerization reaction. The living polymerization of epoxide demonstrates that the Poisson function is suitable for a molecular weight distribution description of polyether produced with catalysts containing a single type of active center. Therefore, poly(propylene oxide)s obtained by different catalytic systems, including C3H5O3K3, C3H5O3K3-CaSO4, C3H5O3K3-crown ether, and C3H5O3K3-CaSC4-crown ether, were characterized by GPC. The peaks obtained by GPC were resolved with a multi-Poisson distribution function. This signifies that there might be multiple active sites instead of single site in these catalytic systems. The addition of calcium sulfate to the catalytic systems not only increased the molecular weight of the polyether but also effected the formation of the active sites. Furthermore, the polymerization of propylene oxide was processed in the presence of the aforementioned catalytic systems. Much useful information concerning the kinetic process of the polymerization was obtained from the GPC data with computer analysis. (C) 2003 Wiley Periodicals, Inc.