Adsorption properties of Pd supported on gamma-Al2O3, TiO2, SiO2, and adsorbed CO and oxygen low-temperature reactivities have been studied using IR spectroscopy, TPD, and pulse titration techniques. The results obtained are compared with the Pd surface structure data. At saturation coverages, weakly bound forms of CO (both linear and bridge-bonded) are the most reactive, their properties depending upon the type of support. Effect of Pd surface layer rearrangement due to CO and/or oxygen adsorption has also been found to be of importance. For mixed carbon monoxide-oxygen adlayer (theta(CO) and theta(O) are comparable), an overall Pd surface disordering occurs to wipeout all support effects.