Measurements of the complex ionic conductivity of a bioactive glass ceramic and related materials are reported for frequencies 0.1 Hz less than or equal to v less than or equal to 500 MHz and at temperatures 10 K less than or equal to T less than or equal to 600 K. Depending on frequency and temperature, the data show blocking-electrode effects, low frequency dispersion, hopping conduction and relaxation processes. The relevance of our results for the surgical application of this material is discussed.