The ceramics of the (1−x)Ba3Co2Fe24O41−xLi4Ti5O12 (x = 0–0·7) system were synthesised by a conventional solid state reaction method. X-ray diffraction revealed a phase transition from Z type hexaferrite (Ba3Co2Fe24O41) to M type hexaferrite (BaFe12O19) at x = 0·2. Upon the occurrence of the phase transition, the temperature stability τf exhibits an inflexion point. For x≧0·4, the τf value began to decrease linearly with increasing values of x. The structural morphology was studied by scanning electron microscopy and indicated that an appropriate additional amount of Li4Ti5O12 hindered grain growth. The microwave properties of the (1−x)Ba3Co2Fe24O41−xLi4Ti5O12 ceramics were investigated. For increasing values of x, the real part of the permeability μ decreased from 12 to 1·3 at 1 GHz and the magnetic losses (tan δμ) first decreased and then increased with increasing values of x. In addition, the real part of the permittivity ϵ increased from 15 to 23, but the dielectric losses (tan δϵ) decreased significantly from 0·1 to 0·0006 at 1 GHz. The best combination of microwave properties was achieved at x = 0·6, yielding the following properties: μ = 2, tan δμ = 0·033, ϵ = 23, tan δϵ = 0·004 and τf = 96 ppm/°C.