Crystallization, also in polymers, is commonly considered as nucleation followed by a growth process. Nevertheless, a complete description of crystallization is far from being achieved. In this work a new experimental technique for temperature control of the sample and determination of its heat capacity during temperature treatment at high cooling and heating rates was developed. Both, crystal nucleation and growth characteristic times were determined simultaneously in the range of temperatures where crystallization occurs – from below glass transition up to equilibrium melting temperature.