A new iron oxophosphate of composition Rb 7 Fe 7 (PO 4 ) 8 O 2 ·2H 2 O has been synthesized and studied by X-ray diffraction, TG and DTA analysis, magnetic susceptibility, neutron diffraction, Mössbauer spectroscopy and ionic conductivity. This compound crystallizes in the monoclinic system with the P2 1 /c space group and the unit cell parameters a=8.224(8)Å, b=22.162(6)Å, c=9.962(6)Å and β=109.41(8)°. Its structure is built up from Fe 7 O 32 clusters of edge- and corner-sharing FeO 5 and FeO 6 polyhedra. Neighboring clusters are connected by the phosphate tetrahedra to form a three-dimensional framework. The Rb + cations and the water molecules are occupying intersecting tunnels parallel to a and c. The presence of water molecules was confirmed by TG and DTA analysis. The magnetic susceptibility measurements have shown the existence of antiferromagnetic ordering below 22K with a weak ferromagnetic component. Additionally, these measurements show evidence for a strong magnetic frustration characterized by |θ/T N |≈12. Powder neutron diffraction study confirms the presence of a long range antiferromagnetic order coupled to a weak ferromagnetic component along the b-axis. The strongly reduced magnetic moments extracted from the refinement support the existence of a magnetically frustrated ground state. The Mössbauer spectroscopy results confirmed the presence of only Fe 3+ ions in both five and six coordination. The ionic conductivity measurements led to activation energy of 0.81eV, a value that agrees with the obtained for other rubidium phosphates.