Abstract: The single crystal of potassium praseodymium metaphosphate (KPrP₄O₁₂) has been obtained by evaporation-solution method and its β type structure has been determined by x-ray diffraction method using MoK_α radiation.The crystal structure analysis characterized this structure as monoclinic with space group C2/c and cell parameters a=7.913(2), b=12.489(3), c=10.659(3)Å, β=110.48(2)°and z= 4. The basic structure units are P₄O₁₂^4- rings arranged in layers along the c axis. Pr³⁺ located between layers is bonded to surrounding eight oxygens. The average distance between praseodymium and coordinating oxygens is 2.468Å.