Abstract: The crystal of potassium europium metaphosphate KEu(PO₃)₄ belongs tothe monoclinic space group P2₁ with unit cell parameters a=7.932(4)Å,b=8.375(1)Å, c=7.261(3)Å, β=92.05(4)°, V=482.0ų, Z=2. The intensities of 979 independent reflections were collected by the PW-1100 four-circle diffractometer. The structure was solved by heavy-atom method and the final R=0.084 after refining by full-matrix least-squares method.The basic structure units are helical ribbons, (PO₃)_n, formed by cornersharing tetrahedra of PO₄. The coordination of the europium anion by oxygen atoms is eight-fold with the geometry of dodecahedra. The shortest Eu-Eu distance is 6.93Å.