The Zn-substituted planar hexaferrite Ba3Co2-xZnxFe24O41 (x = 0-1.2) powders were prepared via a citrate precursor method. With an appropriate sintering aid, ceramics with high density could be obtained after sintering at a temperature of less than 900 degrees C. These ceramics exhibit excellent high-frequency properties such as high initial permeability up to 10.0 with cutoff frequencies above 1.1 GHz. The results show that we have exploited novel promising ferrimagnetic materials well suited for multilayer chip inductors or multilayer chip beads applications in the high-frequency range.