Effects of lithium perchlorate (LiClO(4)) on the crystallization behaviors of poly(ethylene oxide) (PEO) were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and polarized optical microscopy (POM) in PEO/LiClO(4) system. DSC results indicate that there are nucleation effects of LiClO(4) on the crystallization of PEO. But, on the other hand, the coordination of lithium ion with the oxygen ether atoms of PEO can obviously reduce the crystallinity and spherulite growth rate of PEO. This contrary effect of LiClO(4) on the crystallization of PEO in PEO/LiClO(4) complexes system was analyzed and discussed in detail. The Laurizen-Hoffman theory was used to describe the Li-coordinated crystallization kinetics of PEO spherulite. It showed that the nucleation constant (Kg) and folding surface free energy (re) decreased with increasing LiClO(4) contents, and the energy necessary for the transport of segments across the liquid-solid interface (DE) increased on increasing the contents of LiClO(4). (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1935-1943, 2012