Catalysts containing particles of metallic palladium have been synthesized by anchoring metal complex precursors on carbon supports (active carbon, carbon black, ultra-dispersed graphite and diamond). Anchored precursors were obtained by interaction of solutions of tetrachloride or allylcyclopentadienyl palladium complexes with the supports. Based on data on the peculiarities of HgPdCl 4 adsorption on carbon sorbents of different natures, three types of adsorption sites of Pd II ions have been identified and a quantitative evaluation of their strengths made. The size of the Pd crystallite formed upon reduction of the anchored complexes and its catalytic activity in cyclohexene hydrogenation depend upon the strength of the adsorption site. An increase in the strength of the adsorption site leads to a decrease both in the size and catalytic activity of Pd crystallites. The effect observed is associated with a modifying (ligand) action of atoms involved in the adsorption site. Fourier transform IR spectroscopic data indicate that the interaction of C 3H 5PdC 5H 5 with an oxidized diamond surface occurs with participation of the carboxyl groups of the support. According to transmission electron microscopic data, Pd/C catalysts reduced with hydrogen at 300 °C contain Pd particles 10 – 20 Å in size. On increasing the reduction temperature to 600 °C, the dispersion of Pd/diamond remains almost unchanged while the size of the metallic particles on Pd/graphite increases to 100 Å. This difference is due to peculiarities in the interaction of Pd particles with graphite and diamond surfaces in a hydrogen atmosphere. In the structurally insensitive hydrogenation of benzene, the turnover number (TON) activity of the Pd/C catalyst is commensurable with that of Pd/SiO 2, but in the structurally sensitive hydrogenolysis of ethane and hydrogenation of CO to methanol, the TON of Pd/C is one to two orders of magnitude lower, probably due to dissolution of carbon atoms in the Pd particles. Introduction of Zr ions into Pd/C leads to the appearance of a new absorption band at 1600 cm −1 in the IR spectrum of adsorbed CO, an increase in TON activity by 1 – 2 orders of magnitude in methanol synthesis and a drastic decrease in activity in ethane hydrogenolysis, the inhibiting effect of Zr ions being completely suppressed by high-temperature oxidation of the samples. These specific features are similar to those observed earlier for (Pd+Zr)/SiO 2 and Pd/ZrO 2, and seem to be due to the formation of mixed Pd-Zr active sites in the systems under consideration.