The microwave dielectric properties and the microstructures of Sm(Co1/2Ti1/2)O-3 ceramics with B2O3 additions (0.25 and 0.5 wt%) prepared by conventional solid-state route have been investigated. The prepared Sm(Co1/2Ti1/2)O-3 exhibited a mixture of Co and Ti showing 1:1 order in the B-site. Doping with B2O3 (up to 0.5 wt%) can effectively promote the densification of Sm(Co1/2Ti1/2)O-3 ceramics with low sintering temperature. It is found that Sm(Co1/2Ti1/2)O-3 ceramics can be sintered at 1,260 degrees C due to the grain boundary phase effect of B2O3 addition. At 1,290 degrees C, Sm(Co1/2Ti1/2)O-3 ceramics with 0.5 wt% B2O3 addition possess a dielectric constant (epsilon (r)) of 27.7, a Q x f value of 33,600 (at 9 GHz) and a temperature coefficient of resonant frequency (tau(f)) of -11.4 ppm/ degrees C. The B2O3-doped Sm(Co1/2Ti1/2)O-3 ceramics can find applications in microwave devices requiring low sintering temperature.