More than 50 yr. after the proposal of the Dewar-Chatt-Duncanson model for the binding of olefins to transition-metal atoms, the first structurally characterized example of a silver-C2H4 complex [Ag(h2-C2H4)3]+ was obtained with the help of the very weakly coordinating [Al{OC(CF3)3}3]- ion. By contrast, earlier gas-phase investigations only suggested the existence of [Ag(h2-C2H4)x]+ ions (x = 1 and 2). The crystal structure of the title compd. is given and it was compared with DFT calcd. structure. [on SciFinder (R)]