Low-loaded Pd/SiO2 catalysts were characterized by CO and H-2 chemisorption to determine the dispersity of palladium. The reliability of static and pulse-chromatographic adsorption procedures had to be studied and optimized because of the low ratio of Pd surface to support surface. Static and pulse-chromatographic CO adsorption proved to be the preferential methods. IR spectroscopy was used to control the composition of the CO monolayer and to explain apparent Pd dispersity, amounting > 100% in catalysts promoted by small amounts of ZnO. The reliability of H-2 adsorption measurements by the ＇＇back sorption technique＇＇ was partially questioned because a recombination of ab- and adsorbed hydrogen seems to result in an under-determination of Pd dispersity.