Isothermal crystallization behavior of isotactic polypropylene (iPP) synthesized using metallocene catalyst was investigated in this work. The isotacticity of the polypropylene was characterized by C-13-NMR spectroscopy. It was found that the melting temperature (T-m) of the iPP is 123.51degreesC and the crystallization temperature (T-c) is 93degreesC. The iPP synthesized in this work did not show a general increase of T-m with an increase of crystallization temperature T-c, due to the short crystallization time of 20 min and low molecular weight (number average molecular weight = 6,300). The iPP showed a tendency of increasing heat of fusion (DeltaH(f)) with decreasing crystallization temperature. All the spherulites of iPP samples showed negative birefringence. For the iPP sample crystallized at the highest T-c (= 123degreesC, just below T-m), the spherulite showed a pronounced Maltese Cross and a continuous sheaf-like texture aligning radially, which suggests that R-lamellaes are dominant in this spherulite. The crystalline structure of the iPP was also investigated by X-ray diffraction. (C) 2004 Wiley Periodicals, Inc.