Abstract High dielectric constant and low loss ceramics in the system Ba 3 La 2 Ti 2 Nb 2− x Ta x O 15 ( x = 0–2) have been prepared by conventional solid-state ceramic route. Ba 3 La 2 Ti 2 Nb 2− x Ta x O 15 solid solutions adopted A 5 B 4 O 15 cation-deficient hexagonal perovskite structure for all compositions. The materials were characterized at microwave frequencies. They show a linear variation of dielectric properties with the value of x . Their dielectric constant varies from 49.8 to 45.1, quality factor Q u × f from 22,000 to 31,040 GHz and temperature variation of resonant frequency from + 6.9 to − 13.4 ppm/°C as the value of x increases. These low loss ceramics might be used for dielectric resonator (DR) applications.