Dendrimer-metal-nanocomposites (DMNs) were used as precursors to prepare SiO 2-supported monometallic Pt, Cu, and bimetallic Pt–Cu catalysts with Pt/Cu atomic ratios of 1:1 (Pt 50Cu 50) and 1:3 (Pt 25Cu 75). After impregnation of these DMNs onto the support, the catalysts were thermally treated and activated following an optimized protocol. Scanning transmission electron microscopy (STEM) showed that the metal nanoparticles in the dendrimer-derived SiO 2-supported catalysts were smaller and had a narrower size distribution compared with those in conventional catalysts prepared using corresponding metal salts via the wet-impregnation method. Slow deactivation was observed for hydrodechlorination of 1,2-dichloroethane over monometallic Cu catalysts, which showed an activity about one to two orders of magnitude lower than that of the Pt-containing catalysts. Hydrodechlorination of 1,2-dichloroethane over the Pt and Pt 50Cu 50 catalysts produced mainly ethane, and the selectivity toward ethane increased with temperature. For the Pt 25Cu 75 catalyst, the selectivity toward ethane decreased in favor of that of ethylene. The overall activity decreased with increasing Cu loading in the catalysts. Activity based on surface Pt sites suggests the formation of bifunctional surfaces in Pt 25Cu 75 catalyst favoring C Cl bond scission on Cu sites and hydrogenation of intermediate ⋅CH 2CH 2⋅ on Pt sites. In addition, kinetic analyses suggest different reaction mechanisms for hydrodechlorination of 1,2-dichloroethane over Pt and Cu-enriched surfaces in the Pt–Cu bimetallic catalysts.