The quality of the electrode/electrolyte interface is important if impedance spectroscopy is used to seperate the contributions of bulk and grain boundary regions to the electrical response of polycrystalline ionically conducting ceramics. This work focused on a number of parameters related to the sample preparation prior to impedance spectroscopy measurements. To evaluate the influence of the surface roughness samples with different surface roughnesses have been created by polishing them with successive grades of diamond paste down to 1, 6, or 15 mum. Next, samples of all three surface roughnesses were coated with Pt and Au by sputtering and with Al by evaporation. Two samples polished down to 1 mum were coated with Au by evaporation and Cr/Au by sputtering, respectively. The metal layers served as blocking electrodes in impedance spectroscopy measurements, which were carried out in a temperature range from 30 to 300-degrees-C and a frequency range from 1 Hz to 500 kHz. The results were discussed in terms of the various equivalent circuit elements inferred from complex impedance plots. SEM investigations were carried out to characterize optically the ceramic/electrode interface prior to and after measurement.