A new copper-phosphide, was synthesized by a high-temperature solid-state route and salt flux method. The crystal structure of was determined using single crystal X-ray diffraction. crystallizes in the orthorhombic space group Pnnm (No. 58) with unit cell parameters of a ​= ​12.018 (1) , b ​= ​23.762 (2) , and c ​= ​3.984 (1) with Z ​= ​8. crystallizes in a new structure type. A complicated three-dimensional framework built by Cu–Cu and Cu–P interactions hosts Ba cations in According to differential scanning calorimetry, decomposes to and around 1180 (5)K. Theory calculation and thermoelectric measurements confirm the metallic nature of The experimentally measured moderate thermal conductivity of is mainly originated from its complex crystal structure. The Seebeck coefficient of is positive and low, ranging from 10 ​K to 400 ​K.