AgNiO 2 is prepared by reaction of molten silver nitrate with NaNiO 2. Powder X-ray diffraction shows that the compound has the delafossite structure of space group R3m. Magnetic data give evidence for the localization of the 3 d-electrons of most Ni atoms. Electrical conductivity and thermoelectric measurements performed between 4.2 and 300 K on polycrystalline samples show that AgNiO 2 behaves like a semimetal. N-type and p-type charge carriers are created by a slight overlapping of the d band of silver atoms with the σ* antibonding band resulting from the overlapping of the Ni 3 d- and O 2 p-orbitals.