Today, the field of nanotechnology is one of the most important areas of research in most technical disciplines. Polymer nanocomposites are systems consisting of a polymer matrix (continuous phase) and fillers with at least one nanometer-sized dimension (discontinuous phase). The properties of the nanocomposites are influenced by the properties of the polymer matrix and the properties of the filler. The properties of the filler depend on the content and type of filler, the size and distribution of the filler, the specific surface area of the filler, the shape of the particles and the interactions that are established at the matrix/filler interface. Due to the reduction of the size of the filler to the nanosize, new advances in composite research have been made possible. The aim of this study is the influence of multiwalled carbon nanotubes (MWCNT) on the non-isothermal crystallization process of PCL/CNT nanocomposites with different weight rations of MWCTN. PCL/CNT nanocomposites with different CNT content were obtained from a PCL/CNT solution in THF. The thermal characterization of the PCL/CNT nanocomposite was performed using the differential scanning technology (DSC) technique in non-isothermal conditions. From the DSC values, the activation energy (Ea), the half-time of crystallization (t1/2) and the total time of crystallization (tt) were determined. Ea was determined according to the Kissinger and Flynn, Wall, Ozawa (FWO) models.