The aqueous mixing technique-assisted solid-state method was used to synthesize Ba(Co0.7Zn0.3)1/3Nb2/3O3 (BCZN) ceramics. The optimum pH of the slurry used for the BCZN synthesis was determined from plots of the Zeta potential (ζ) and the viscosity versus pH. The as-prepared materials were characterized by XRD, TG-DTA, SEM and EDS. The microwave dielectric properties are measured using a network analyzer. Ba5Nb4O15 and Ba8(Co,Zn)1Nb6O24 secondary phases were found on the surface of all samples. The ceramic materials sintered at 1350 °C were found to have a high quality factor Qf of 96132, a high dielectric constant εr of 34.5 and near-zero temperature coefficient of the resonant frequency τf of 0 ppm/°C measured at 6 GHz.