A new nickel germanide, NiGe2, was synthesized under high pressure and temperature condition and the crystal structure was solved by the Rietveld analysis of the powder X-ray diffraction data. Single phase NiGe2 was obtained from the stoichiometric mixture of elemental components by the reaction at 5.5 GPa and 700 °C. The compound crystallizes into orthorhombic structure with the space group Cmca, isostructural with CoGe2. Lattice parameters were determined to be a = 10.830(5) angstroms, b = 5.763(3) angstroms, c = 5.762(3) angstroms. The structure contains isolated Ni-Ni bonds along the a-axis. The compound is a metallic conductor with a temperature independent susceptibility.