An inversion technique is developed to reconstruct the temperature distribution over the thickness of a part during polymer processing using the surface temperature measurement. The algorithm is validated using surface temperature data generated numerically from a number of theoretical temperature profiles developed during polymer flows. The technique is then applied to the injection stretch blow molding process. In this process a preform is injection molded, stretched to its final length and then inflated. A single stage AOKI machine is used for the experiments. An infrared camera is employed to measure the surface temperature of the preform with time after it is taken out of the injection mold. The initial temperature distribution in the preform and its temperature evolution before stretching and inflation are predicted.