High-dielectric constant and low-loss ceramics in the (Zn1-xCox)Ta2O6 ceramics have been prepared by the conventional mixed oxide route and their microwave dielectric properties have been investigated. A phase change or crossover from ZnTa2O6 to CoTa2O6 occurred at x=0.07 and was completed at x=0.11 and it tends to form a continuous solid solution elsewhere. An over-sintered specimen would lead to a slight decrease in the density resulting in a decline of the dielectric constant and the Q x f value. The specimen with x=0.05 possessed an excellent combination of microwave dielectric properties: epsilon(r)similar to 38.47, Q x f similar to 112 000 GHz, and tau(f)similar to 11.2 ppm/degrees C. It is proposed as a candidate material for today's 3G passive components and especially small-sized GPS patch antennas.