The crystal structure and luminescence properties of flux-grown crystals of a new europium(III) fluoride-silicate, K5Eu2FSi4O13, are reported. The structure consists of octahedral dimers of the composition [Eu2O10F], which are linked by unbranched tetrasilicate chains to form a 3-D framework with 5- and 6-ring channels parallel to the b axis where the K+ cations are located. The sharp peaks in the room-temperature emission spectrum are assigned. The number of lines in the region for the D-5(0) -> F-7(0) transition and the relative intensities of the D-5(0) -> F-7(1) and D-5(0) -> F-7(2) transitions confirm the presence of two local Eu3+ environments and strongly distorted Eu3+-ligand surroundings. The room-temperature fluorescence decay curves are well fit by a single-exponential function yielding a lifetime value of about 2.0 ms. Crystal data: monoclinic, space group P2(1)/m, a = 7.1850(2) angstrom, b = 5.7981(2) angstrom, c = 18.1675(6) angstrom, beta = 92.248(2)degrees, and Z = 2.