The crystal structure of KTiPO 5 , determined by a simultaneous use of the tangent-formula method and the Patterson method, is described in space group Pn 2 1 a . Lattice constants are: a = 12.814 Å, b = 10.616 Å, c = 6.404 Å. This compound is a monophosphate whose chemical formula must be written KTiOPO 4 . Distorted TiO 6 groups have a short Ti–O distance.