Powder X-ray diffraction data for pi-Ti2O(PO4)(2).2H(2)O (pi-TiP) is indexed in a monoclinic cell [a = 5.067(4), b = 10.898(3), c = 14.533(8) Angstrom, beta = 96.0(1)degrees]. Structural correlations with other titanium phosphates are discussed. The reaction of pi-TiP with molten MNO3 (M = Na, K) originates new metal phases with a KTP-type formula, pi-M0.5H0.5TiOPO4. These compounds maintain the fibrous morphology of their precursor. The reactions are monitored by thermogravimetric analysis. Thermal decomposition of the novel compounds is described. (C) 2002 Elsevier Science Ltd. All rights reserved.