Single crystals of the new copper(II) germanate K2Cu3Ge5O14 have been grown. Conditions for the synthesis are reported. The crystal structure of this material has been established by single-crystal X-ray diffraction:  triclinic, space group P1̄ a = 6.1859(4) Å, b = 7.1484(5) Å, c = 7.8491(5) Å, α = 82.150(1)°, β = 72.072(1)°, γ = 80.773(1)°. The structure consists of layers of composition formed by GeO4 tetrahedra and GeO6 octahedra. The cohesion among them is established through chains of edge-sharing CuO5 square pyramids and CuO6 octahedra. This 3D structure contains a two-dimensional channel network were potassium ions are hosted. The downward deviation from Curie−Weiss behavior observed under 30 K in the molar magnetic susceptibility of K2Cu3Ge5O14 is attributed to the effect of the crystal field splitting of the ground term.