The crystallization behavior of a new sequential polyester constituted by glycolic acid and 4-hydroxybutyric acid has been studied under nonisothermal conditions. Nonisothermal melt crystallization has been followed by means of hot-stage optical microscopy (HSOM), with experiments performed at different cooling rates. Two crystallization regimes have been found, which is in good agreement with previous isothermal studies and with the different spherulitic morphologies that were observed. The kinetics of both glass and melt crystallizations has also been studied by differential scanning calorimetry (DSC) and considering the typical Avrami, Ozawa, and Caze analyses. Only the last gave Avrami exponents, which were in good agreement with those measured under isothermal conditions, suggesting a spherulitic growth with a predetermined nucleation. lsoconversional data of melt and glass nonisothermal crystallizations have been combined to obtain the Hoffman and Lauritzen parameters. Results again indicate the existence of two crystallization regimes with nucleation constants close to those deduced from isothermal DSC experiments. (C) 2007 Wiley Periodicals, Inc.