An extension of the modeling proposed previously has been examined for the irreversible melting kinetics of polymer crystals on heating with response to temperature modulation. The previous modeling has been successful in the explanation of the frequency dependence of the apparent heat capacity obtained with temperature modulated DSC in the melting region of poly(ethylene terephthalate), polyethylene and poly(caprolactam). In the present work this modeling was extended to explain an unusual behavior reported by Schawe et al. for poly(epsilon -caprolactone) and syndiotactic polypropylene, in which the latent heat gave a substractive effect to the real part of the apparent heat capacity. A retardation of the melting rate coefficient in response to temperature change has been considered. The retardation implies an activation process in the melting kinetics of polymer crystals. (C) 2001 Elsevier Science Ltd. All rights reserved.