Present work introduces a new kind of microwave dielectric ceramic, Ba4Ti3P2O15. Ba4Ti3P2O15 ceramic can be prepared by solid state reaction method and be well densified after being sintered at above 1175 degrees C for 4 h in air. All the XRD patterns can be fully indexed as single-phase structure. The best microwave dielectric properties can be obtained in ceramic sintered at 1200 degrees C for 4 h with permittivity about 20.7, Q x f about 42, 210 GHz and TCF about 37 ppm degrees C-1. Measurements of the microwave dielectric properties of Ba4Ti3P2O15 ceramic revealed the existence of a maximum in the temperature dependence of the dielectric loss because of the defect dipoles relaxation. (C) 2009 Elsevier B.V. All rights reserved.