Abstract The low temperature sintering behaviors and high frequency properties of Cu-modified Co 2Z hexaferrites have been investigated. Normally, Cu-modified Co 2Z hexaferrite is difficult to be sintered at temperature lower than 1150 °C. By adding a small amount of sintering aid Bi 2O 3, Cu-modified Co 2Z ceramics with high density (more than 95% theoretical density) have been prepared successfully after sintering below 900 °C. The microstructures and properties are significantly influenced by the sintering temperature, the amount of Bi 2O 3 addition, as well as Cu content. The modified hexaferrite ceramics sintered at 900 °C, exhibited excellent high frequency properties, such as high initial permeability up to 6.6, high quality factor more than 30, high resistivity over 10 9 Ω cm and good thermal stability. The experimental results show that these materials have a great potential as soft magnetic media for high frequency MLCIs applications.