Microcrystals of the first ammonium-thorium phosphates, (NH4)(2)Th(PO4)(2)center dot H2O (tetragonal, i4(1)/amd, a = 7.0192(4) angstrom, c = 17.9403(8) angstrom) and NH4Th2(PO4)(3) (monoclinic, C2/c, a = 17.880(6) angstrom, b = 6.906(1) angstrom, c = 8.152(2) angstrom, beta = 104.39(2)degrees) were hydrothermally obtained from a Th(NO3)(4)-CO(NH2)(2)-H3PO3-H2O system (T = 180 degrees C). In both cases, the structure consists of a three-dimensional framework with PO4 tetrahedra coordinated to Th atoms (ThOn polyhedra, where n = 8 or 9, for the tetragonal or monoclinic phase, respectively). The ammonium ions (and water molecules) are located in the tunnels.