The microwave dielectric properties and the microstructures of LaAlO3 ceramics with B2O3 additions (0.25 - 1 wt%) prepared with conventional solid-state route have been investigated. Doping with B2O3 (up to 0.5 wt%) can effectively promote the densification of LaAlO3 ceramics. It is found that LaAlO3 ceramics can be sintered at 1400 degreesC due to the liquid phase effect of B2O3 addition. The Q x f value as well as the dielectric constant decreases at higher B2O3 doping level ( 1 wt%) due to the increase of boundary phases. At 1460 degreesC, LaAlO3 ceramics with 0.5 wt% B2O3 addition possesses a dielectric constant ( er) of 22.9, a Q x f value of 44700 ( at 9 GHz) and a temperature coefficients of resonant frequency (tau(f)) of - 36 ppm/degreesC. The B2O3-doped LaAlO3 ceramics can find applications in microwave devices requiring low sintering temperature. (C) 2003 Kluwer Academic Publishers.