Dense disks of La1-xSrxCoO3-delta materials were prepared and characterized by electrochemical permeability experiments. Our results confirm that these materials possess relatively high ionic conductivity, and this is greatly enhanced by Sr additions. The ionic conductivity of these materials at temperatures of about 1000 degrees C may exceed the conductivity of the most widely used electrolyte materials. However, the permeability experiments could not be fitted by a relatively simple model behaviour derived from the expected defect chemistry, in which the electrode overpotentials are neglected. Significant overpotential contributions are thus expected.