Two new isostructural mixed-metal phosphates, BaTeMO4(PO4) (M = Nb5+ or Ta5+), have been synthesized as bulk phase powders and single crystals by standard solid-state techniques using BaCO3, TeO2, Nb2O5 (or Ta2O5), and NH4H2PO4 as reagents. The materials have novel layered crystal structures consisting of [M5+O6/2](-) corner-sharing octahedral chains that are connected to [Te4+O4/2](0) polyhedra and [P5+O2/1O2/2](-) tetrahedra. The Ba2+ cations reside between the layers and maintain charge balance. The Te4+ cations are in asymmetric coordination environments attributable to their lone pairs. The Nb5+ distorts along the local C-4 direction of its octahedron resulting in a "short-long-short-long" Nb-O-Nb bond motif. The Nb5+ cation displaces away from the oxide ligands that are bonded to Te4+ or P5+ cations, attributable to the structural rigidity of the TeO4 and PO4 polyhedra. Thus, the TeO4 and PO4 polyhedra support and reinforce the intraoctahedral distortion observed within the NbO6 octahedra. Infrared and Raman spectroscopy, thermogravimetric analysis, and ion-exchange experiments are also presented. Crystal data: BaTeNbO4(PO4), orthorhombic, space group Pbca (No. 61), with a = 6.7351 (9) Angstrom, b = 7.5540(10) Angstrom, c = 27.455(4) Angstrom, V 1396.8(3) Angstrom and Z = 8; BaTeTaO4(PO4), orthorhombic, space group Pbca (No. 61), with a = 6.734(2) Angstrom, b 7.565(3) Angstrom, c = 27.435(g) Angstrom, V = 1372.6(8) Angstrom(3) and Z = 8.