A single-phase YBa 3 Ti 2 O 8 5 ceramic located in the BaO-rich corner of the BaO-Y 2 O 3 -TiO 2 ternary system was synthesized. The dielectric properties of this material (permittivity = 29, quality factor Q = 1000) are reported here for the first time. Compositions with the BaO:Y 2 O 3 :TiO 2 ratio equal to 6:1:5 and 5:1:4 were also synthesized. The Y615 ceramic consists of two phases (YBa 3 Ti 2 O 8 5 and BaTiO 3 ), and the Y514 ceramic consists of three phases (YBa 3 Ti 2 O 8 5 , BaTiO 3 , and Y 2 TiO 5 ). They are dense ceramic composites.