A new method is developed to obtain the kinetic parameters of polymer crystallization from measurements of the transformation rate usually done at (but not restricted to) constant heating or cooling rates. It can be considered a generalization of the Fiedman's isoconversional method to deal with the HoffmanLauritzen temperature dependence. Apart from delivering the U* and Kg parameters as a function of the transformed fraction, this method allows to predict the crystallization course for an arbitrary thermal history. It has been applied to the crystallization of PET and PA6 samples, monitored by differential scanning calorimetry (DSC). (C) 2017 Elsevier Ltd. All rights reserved.