The dispersion of supported platinum-containing catalysts was determined by the pulse chemisorption technique. Two catalyst loadings for the monometallic catalyst and a bimetallic catalyst were investigated: 0.3%Pt/Al2O3, 0.6%Pt/Al2O3 and 0.3%Pt-0.3%Re/Al2O3. Results confirm the usually observed trend that dispersions after oxidation are higher than those after reduction. The redispersion profiles peaked at a sintering temperature of 550 degrees C for all catalysts studied. However, the bimetallic catalyst was found to redisperse at all treatment temperatures while the monometallic catalysts sinter and redisperse at various treatment temperatures. The atomic migration model was proposed as a suitable model for the prediction of the particle size distribution (PSD) as it lends itself easily to the prediction of sintering and redispersion phenomena. The computer simulation for the catalyst resulted in the calculation of dispersion generated PSD, for the oxygen sintered catalyst and the reduced catalyst after sintering. The general PSD profiles for both sintering situations show the same pattern of shift to larger particle sizes after specific temperatures. At a temperature transition of 500-550 degrees C, the PSD shifted to lower particle sizes for the 0.3%Pt/Al2O3 and the 0.6%Pt/Al2O3 catalysts. Above 550 degrees C, the PSD shifted to higher particle sizes with larger spreads. On the bimetallic catalyst, the shift of the PSD to the left occurred at two temperature transitions: one at 500-550 degrees C and the other at 750-800 degrees C. The selective aromatic yield was studied on a catalyst sintered at various temperatures and reduced at 500 degrees C. At 500 degrees C, toluene was the sole product of the reforming reaction of n-heptane on 0.3%Pt/Al2O3 catalyst; on the bimetallic catalyst surface, toluene as the sole product of reaction occurred a sintering temperature of 800 degrees C. Although the PSD for the sintered PSD on 0.6%Pt/Al2O3 catalyst was quite similar to that of the 0.3%Pt/Al2O3 catalyst, no aromatization products were formed on this catalyst. Aromatization selectivity was attributed to three-atom ensembles of triangular symmetry of small Pt aggregates (Biloen et al., 1980; Paal, 1980, 2003). If this reaction occurs, it can indicate the presence of facets with (I 11) symmetry produced during sintering and redispersion.