Crystalline complexes of norbornadiene with silver tetrafluoroborate have been obtained both from anhydrous and aqueous solution. While both solutions yield complexes of stoichiometry AgBF4•C7H8 and 2AgBF4•3C7H8, those from the aqueous solutions also contain water of crystallization. The infrared spectra show that norbornadiene is similarly complexed in both the anhydrous and hydrated complexes but that the coordination in the 1:1 complex is different from that in the 2:3 complex. The anhydrous and hydrated 1:1 complexes have the same X-ray diffraction powder patterns while those of 2:3 complexes are different.