The family of titanium Nasicon-phosphates of generic formula (M0.50Ti2)-Ti-II(PO4)(3) has been revisited using hydrothermal techniques. Two phases have been synthesized: (Mn0.50Ti2)-Ti-II(PO4)(3) (MnTiP) and (Co0.50Ti2)-Ti-II(PO4)(3) (CoTiP). Single crystal diffraction studies show that they exhibit two different structural types. (Mn0.50Ti2)-Ti-II(PO4)(3) phosphate crystallizes in the R-3 space group, with the cell parameters a = 8.51300(10) angstrom and c = 21.0083(3) angstrom (V = 1318.52(3) angstrom(3) and Z = 6). The Coo.5"Ti2(P04)3 phosphate crystallizes in the R-3c space group, with a = 8.4608(9) angstrom and c = 21.174(2) angstrom (V = 1312.7(2) angstrom(3) and Z = 6). These two compounds are clearly related to the parent Nasicon-type rhombohedral structure, which can be described using [Ti-2(PO4)(3)] framework composed of two [TiO6] octahedral interlinked via three [PO4] tetrahedra. P-31 magic-angle spinning nuclear magnetic resonance (MAS-NMR) data are presented as supporting data. Curie-Weiss-type behavior is observed in the magnetic susceptibility. The phases are also characterized by IR spectroscopy and UV-visible. (c) 2009 Elsevier Ltd. All rights reserved.