Isothermal and non-isothermal melt crystallization kinetics of isotactic polypropylene (iPP) were investigated via differential scanning calorimetry (DSC). Isothermal melt crystallization kinetics were analyzed using the Avrami equation. An Avrami exponent close to three was obtained fur iPP, which implies growth of three-dimensional spherulitic superstructures following heterogeneous nucleation. Nonisothermal crystallization kinetics data obtained from DSC in conjunction with a non-linear regression method were employed to estimate the kinetic parameters of mathematical models describing the non-isothermal crystallization of iPP. The results suggest that the available mathematical models are not successful in describing the non-isothermal crystallization of iPP over a wide range of cooling rates. It was found that the non-isothermal crystallization kinetics of iPP, over a wide range of cooling rates, could best be described by modifying the Ozawa model to include induction times. (C) 2001 Elsevier Science Ltd. All rights reserved.