BaTiO3 ceramics with different acceptor concentrations of potassium at A-site Ba1-x K (x) TiO3-x/2 (BKT) were prepared by solid-state processes. The solution limit of potassium in BKT is determined to be 1 mol%. Furthermore, electrical conduction behaviours were investigated in the temperature range of 300-800 A degrees C by analysing impedance spectra and were found extremely depending on processing and measurement conditions. When annealed at 800 A degrees C and measured in an atmosphere of dry N-2, BKT is a mixed oxide ion/electron conductor and its ionic transference number decreases with increasing temperature. But when annealed at 800 A degrees C and measured in an atmosphere of dry air and O-2, BKT is a p-type semiconductor with a transition from a trapped holes' conduction to activated holes' conduction as temperature increases. On exposure of BKT to an atmosphere of wet N-2, BKT is a proton conductor in the temperature of 300-550 A degrees C; however, it reverts to a p-type semiconductor above 550 A degrees C as water is lost from the sample.