Pt-Sn/Al2O3 catalysts; Pt (0.35 wt.%), Sn (0.42 wt.%) and chlorine (similar to1.0 wt.%) were prepared by incipient wetness impregnation and characterized by nitrogen adsorption-desorption, NH3 adsorption microcalorimetry and H-2-O-2 titrations. In catalysts with almost similar values of S-BET (170-180 m(2) g(-1)), total acidity (0.32-0.36 mmol NH3 g(-1)), a significant variation in Pt dispersion was observed with the difference in meso pore size distribution in 20-100 Angstrom diameter range. As the vol.% in 20-100 Angstrom range is increased from 18 to 63%, the Pt dispersion increased from 57 to 81%. A greater abundance of relatively narrow meso pores (20-100 Angstrom diameter) facilitate the fine dispersion of Pt moieties on the alumina surface. At least, a 30% fraction of the total pore volume should lie in 20-100 Angstrom pores in order to obtain a reasonably good Pt dispersion (similar to75%). Although, a further increase of volume in these pores from 30 to 60% improves the Pt dispersion, but decreases the total pore volume presumably due to a sharp decline in larger pores (100-200 Angstrom) which contribute more towards the pore volume. (C) 2002 Published by Elsevier Science B.V.