Temperature-programmed oxidation (TPO) experiments were used to evaluate the performance of uniformly (standard) and nonuniformly (zoned) distributed Pt/Al2O3 catalysts after homogeneous and heterogeneous thermal degradation. Both catalysts were homogeneously aged in an oven by exposing the entire catalyst to 750 degrees C in air for 4 h at atmospheric pressure. In heterogeneous aging, only the back of the catalysts was exposed at 675 degrees C, whereas the temperature at the inlet section did not exceed 550 degrees C. This was accomplished by introducing pulses of C3H6 and O-2, with an inert gas between each pulse, for 50 cycles and using the heat generated by the exothermic oxidation reaction to thermally age zones of the samples. The zone-coated catalyst, with more Pt concentrated in the front of the monolith, showed better performance than the standard sample after heterogeneous aging. The reason is that most of the Pt in the zoned sample, which was located in the front half, was not affected by the more significant aging at the back of the monolith. On the other hand, at a higher total flow rate and higher temperature, the performance of the homogenously aged zoned catalyst was worse than that of the standard sample, because the effect of the Pt-rich upstream area of the zoned catalyst was lost through the formation of larger particles, widening the reaction zone into the less Pt-rich downstream region.