The control of mold surface temperature is an important factor that determines surface morphology and its gradient in thickness direction, frozen orientation and cooling stresses close to sample skin and also mold surface replicability in injection molded products. In this work, the temperature on the mold surface was controlled by thin (high electrical conductivity carbon black loaded polyimide composites) thermally active films. A thin polymeric layer was used to insulate the thermally active films from the mold. The thickness of this layer is a very important parameter since an increase of its thickness gives rise to an increase of the heating rate but also to a decrease of the subsequent cooling rate. A computer regulating the electrical power, on the basis process variables ,controlled the temporal variation of temperature in films . Surface temperature evolution was monitored during the process. The surface temperature heating rate was varied in the interval of 50-70°C/sec and upon contact with the polymer the surface temperature decreased back to 40°C within about 2 secs; the over all cycle time increased only slightly. The effect on cross section sample morphology of samples of PS and iPP were analyzed and discussed on the basis of the recorded temperature evolution.