Single crystals of a new mixed-valent iron phosphate Na 1/2 Cu 4/3 Fe 2 (PO 4 ) 3 have been synthesized by a flux method and structurally characterized from X-ray diffraction data. Crystal data: space group P1¯; a=6.2882(1)Å; b=8.0459(1)Å; c=9.3255(1)Å; α=105.881(1)°; β=107.202(1)°; γ=101.467(1)°; Z=2; R1=0.03; wR2=0.093. The three-dimensional structure was found to be closely related to that of the well known Howardevansite structural type. It results from infinite chains of CuO 5 and FeO 6 polyhedra, joined together by (Cu,□)O 6 octahedra and PO 4 tetrahedra by corner-sharing. The large cavities in framework are occupied by Na + ions. The magnetic susceptibility study revealed an antiferromagnetic behavior with Neel temperature of approximately 40K. The Mössbauer spectroscopy confirmed the presence of iron in both +2 and +3 oxidation states.