The vaporization behavior by heating of an antioxidant additive 2,6-di-tert-butyl-p-cresol (BHT) in polypropylene (PP) was studied. BHT vaporized from PP plates under the stream of air at 70–100°C for 0–3000 min was absorbed to the Tenax GC adsorbent column, and the precentage recoveries of BHT increased linearly with the square root of time: t1/2. There were no considerable differences between the vaporization behavior of BHT by heating under the stream of air and that of nitrogen. BHT does not act as an antioxidant at temperature below 120°C. The percentage recoveries of BHT from PP plates at 90–120°C under a nitrogen stream increased linearly with t1/2 until about 70% of the recovery. At temperature below 80°C, the linear relations still held. The vaporization also proceeded at the temperature below the melting point of BHT. Both the sample thickness and the temperature greatly influenced the vaporization rate of BHT in PP, and the Arrhenius plots of the logarithmus of the specific rate vs. the reciprocal of the absolute temperature at 70–120°C showed an approximately straight line. Triolein coexisted with interrupted BHT vaporization. However, the PP plates containing 0.2 wt % of olive oil showed the same vaporization behavior of BHT as that of the original PP plates free from oils at 80 and 100°C. The decreasing rate of BHT in PP by heating under air obeyed first-order kinetics. © 1993 John Wiley & Sons, Inc.