The phases, microstructure and microwave dielectric properties of ZnTiNb2O8 ceramics with BaCu(B2O5) additions prepared by solid-state reaction method have been investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The pure ZnTiNb2O8 ceramic shows a high sintering temperature of about 1250 degrees C. However, it was found that the addition of BaCu(B2O5) lowered the sintering temperature of ZnTiNb2O8 ceramics from above 1250 degrees C to 950 degrees C due to the BCB liquid-phase. The results showed that the microwave dielectric properties were strongly dependent on densification, crystalline phases and grain size. Addition of 3 wt% BCB in ZnTiNb2O8 ceramics sintered at 950 degrees C afforded excellent dielectric properties of epsilon(r) = 32.56, Q x f = 20,100 GHz (f = 5.128 GHz) and tau(f)= -64.87 ppm/degrees C. These represent very promising candidates for LTCC dielectric materials. (C) 2011 Elsevier B.V. All rights reserved.