This work is devoted to the study of interactions between Pd and Bi in Pd-Bi/SiO2 catalysts and their connection with activity and selectivity of those systems in the selective oxidation of glucose and lactose. In the oxidation of glucose, high activity and selectivity of Pd-Bi/SiO2 systems having higher bismuth content were observed. For those systems the formation of BiPd and Bi,Pd took place. In the case of lactose oxidation better catalytic properties were found for Pd-Bi/SiO2 systems with a small amount of bismuth, where mainly a binary alloy BiPd is formed. (c) 2006 Elsevier B.V. All rights reserved.