The crystal structure of Ti2O2H(PO4)[(NH4)(2)PO4](2) was solved for synchrotron X-ray powder diffraction data. The unit cell is orthorhombic, a = 63943(8) Angstrom, b = 10. 106(1) Angstrom, c = 10.850(2) Angstrom, space group Pmna, Z = 2. This compound has a layered structure with the layers stacking in the direction of the b-axis. The layer is built up from TiO6 Octahedra and PO4 tetrahedra. The phosphorus atom exists in two crystallographically different sites corresponding to orthophosphate and dihydrogenphosphate groups. There are also two crystallographically different titanium atoms joined alternately by oxo and phosphate bridges forming one-dimensional chains advancing in a zigzag manner along the c-axis. These chains are then tied together by the orthophosphate group into layers. The layers contain cavities in which half the ammonium ions reside. The remaining ammonium ions are located in the interlayer space.