The reaction of terminal zinc hydrides with palladium(0) species afforded an unprecedented [η2-Zn2Pd] trimetallic complex through the reductive elimination of H2. In contrast, the reaction of zinc hydrides with a nickel(0) reagent gave σ-Zn-H coordination complexes with no direct Zn-Zn bonding. Computational studies indicated that an oxidative addition/reductive elimination process at the palladium center might be responsible for the formation of a covalent Zn-Zn bond.