In order to develop low-temperature-fired soft ferrites used for radio frequency devices, the effects of PbO–CuO glass addition on both the sintering behavior and the magnetic properties of Co 2Z hexagonal ferrite were investigated. PbO–CuO glass, which has a low melting point, can be used as a sintering aid for Co 2Z hexagonal ferrite, reducing the sintering temperature to 950–1000°C. However, either excess addition of glass or too high sintering temperatures produced the secondary phase (M phase) in Co 2Z hexagonal ferrite, which causes the degradation of the magnetic properties. The 90% relative density, initial permeability of 7–8, the highest Q (40–50) at room temperature, and the resonance frequency above 1 GHz were all obtained for the sample with 2 wt% glass addition sintered at 1100°C for 4 h.