The interest in the study of Ge:Sb:Te thin films is due to their use as optical and electrical memory materials. Both of these applications are based on the structural change from the amorphous to the crystalline state. Thus, understanding of the mechanism of crystallization in this material is important from basic and technological points of view. In this work we have studied the kinetics of the crystallization of Ge:Sb:Te films prepared by thermal evaporation. For that, in situ resistance and capacitance measurements during heating were used. The transformation kinetics from the amorphous to the crystalline state were analyzed using the Kissinger model, from which the activation energy of the crystallization process is obtained. Using x-ray diffraction, Raman spectroscopy and optical microscope measurements, we have observed that during heating at; different heating rates, crystallization of the film is accompanied by the segregation of micrometric inclusions formed by amorphous tissue, perhaps some segregated impurities and crystalline tellurium particles. The number and size of these inclusions depend on the heating rate. From our measurements we found that the capacitance measurements is a sensitive method by which to analyze the crystallization process in thin films. It provides additional information not obtained using other methods.