Crystals of NaEuP2O7 have been grown by the flux technique and characterized by X-ray diffraction. Single crystal structure of NaEuP2O7 has been solved, for the first time; it crystallizes in the monoclinic P2(1)/n space group with lattice parameters : a = 5.238(2), b = 8.443(4), c = 12.486(6) Angstrom, beta = 91.404degrees (2), V = 552.0(4) Angstrom(3), Z = 4. The crystal structure has been refined yielding a final R(F-2) = 0.049 and R-w(F-2) = 0.138 for 1313 independent reflections (F-o(2) greater than or equal to 2sigma(F-o(2))). In this structure, the PO4 tetrahedral are linked by bridging oxygen to give P2O7 groups, these groups are connected to the EuO8 polyhedron by sharing two oxygen corners to form three-dimensional framework in which channels are noticed and where the sodium ions are located. The frequencies of the vibrational modes of the crystal were obtained from measurements of the infrared spectra. (C) 2004 Elsevier Ltd. All rights reserved.